{"id":1272,"date":"2026-10-20T18:30:00","date_gmt":"2026-10-20T13:00:00","guid":{"rendered":"https:\/\/www.graveiens.com\/blog\/?p=1272"},"modified":"2026-10-27T12:00:10","modified_gmt":"2026-10-27T06:30:10","slug":"alt-text-stem-images","status":"publish","type":"post","link":"https:\/\/www.graveiens.com\/blog\/alt-text-stem-images\/","title":{"rendered":"Alt Text for STEM Images: A Practical Guide for Publishers (with Examples)"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><em>Last updated: October 2026<\/em><\/p>\n\n\n\n<div class=\"wp-block-group key-takeaways\"><div class=\"wp-block-group__inner-container is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading\">Key takeaways<\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Alt text for STEM images should name the image type and state the one insight the reader needs. The detail belongs in a separate long description.<\/li>\n\n\n\n<li>Graphs, geometry diagrams, chemical structures and circuits usually need both a short alt and a long description. Decorative images need an empty alt.<\/li>\n\n\n\n<li>Equations should be coded as MathML wherever the reading system supports it. Images of math with alt text are a fallback, not the goal.<\/li>\n\n\n\n<li>In EPUB, a plain hyperlink to the long description, tied to the image with aria-details, is the most reliable method, according to the DAISY Knowledge Base.<\/li>\n\n\n\n<li>AI can draft descriptions, but research on STEM images still finds gaps in accuracy and structure. A subject expert has to review every draft.<\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n<p class=\"wp-block-paragraph\">Writing alt text for STEM images is harder than writing it for photos. A chart, a geometry figure or a reaction scheme carries the lesson itself. A vague description takes that lesson away from blind and low-vision readers.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This guide is for publishers and production teams. It shows how to split short alt text from long descriptions, gives worked examples for six common image types and covers math and chemistry notation. It also walks through a review workflow, safe use of AI drafts and the factors that drive cost.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Want to see the method on your own figures? <a href=\"https:\/\/www.graveiens.com\/#contact\">Send 25 images for free sample alt text<\/a>.<\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What makes alt text for STEM images different?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">STEM alt text has to carry meaning, not appearance. A reader using a screen reader needs the variables, relationships and labels that a sighted student would use to answer a question. Writers must understand the subject and follow the surrounding text. They must avoid giving away answers and make units, subscripts and operators read aloud correctly.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A photo of a campus building can be described by almost anyone. A titration curve cannot. The writer has to know which features matter: the equivalence point, the buffer region, the axis units. Everything else is noise.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Three things set STEM images apart:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>The image is often the content.<\/strong> The W3C&#8217;s tutorial on complex images groups graphs, charts and diagrams that the page text relies on into one category. It says these need a two-part text alternative: a short description plus a long one.<\/li>\n\n\n\n<li><strong>Context changes the description.<\/strong> The same cell diagram needs different words in a grade 7 workbook and in a university histology text.<\/li>\n\n\n\n<li><strong>Assessment rules apply.<\/strong> In a quiz or test item, the description can only state what a sighted student is given. If the figure asks students to find x, the alt text must not say what x is.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>In short:<\/strong> STEM alt text is subject writing. Treat it like editing, not like tagging.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Short alt vs long description: when do you need both?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Use short alt text alone when one sentence gives a reader everything the image adds. Add a long description when the image holds structured information, such as data points, labeled parts, a sequence or spatial relations, that a single sentence cannot carry. Most graphs, technical diagrams, chemical structures and circuits in textbooks need both.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The DAISY Knowledge Base makes the same point from the reader&#8217;s side. Users want a very brief alt, because they must listen to all of it before they can move on. The alt should help them decide whether to open the extended description.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">The TIDE pattern for STEM descriptions<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">We use a simple pattern to keep every description consistent. We call it TIDE.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Step<\/th><th>What it means<\/th><th>Where it goes<\/th><\/tr><\/thead><tbody><tr><td><strong>T<\/strong>ype<\/td><td>Name the image type: line graph, structural formula, circuit diagram.<\/td><td>Short alt<\/td><\/tr><tr><td><strong>I<\/strong>nsight<\/td><td>State the one thing the figure is there to show.<\/td><td>Short alt<\/td><\/tr><tr><td><strong>D<\/strong>etails<\/td><td>Axes, values, labels, bonds or connections, in a set reading order.<\/td><td>Long description<\/td><\/tr><tr><td><strong>E<\/strong>xit<\/td><td>Tell the reader where the long description is and how to get back.<\/td><td>Short alt or link text<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Quick check: does this image need a long description?<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Answer these four questions for each figure. One &#8220;yes&#8221; usually means you write a long description.<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Would a student need exact values, labels or positions from the image to follow the text or answer a question?<\/li>\n\n\n\n<li>Does the image show a sequence, a cycle or a set of connections?<\/li>\n\n\n\n<li>Is the information missing from the caption and the body text?<\/li>\n\n\n\n<li>Would your short alt run past two sentences if you tried to include everything?<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">If every answer is &#8220;no&#8221;, short alt is enough. If the image adds nothing, mark it decorative with an empty alt attribute.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1600\" height=\"770\" src=\"https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/weak-vs-strong-stem-alt-text.webp\" alt=\"Comparison of weak and strong alt text for STEM images. Weak alt text uses labels like Graph, repeats the caption, lists colors, gives away quiz answers and garbles symbols. Strong alt text names the type and insight, adds what the caption leaves out, states variables, shows only what students are given and spells out notation.\" class=\"wp-image-1269\" srcset=\"https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/weak-vs-strong-stem-alt-text.webp 1600w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/weak-vs-strong-stem-alt-text-300x144.webp 300w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/weak-vs-strong-stem-alt-text-1024x493.webp 1024w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/weak-vs-strong-stem-alt-text-768x370.webp 768w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/weak-vs-strong-stem-alt-text-1536x739.webp 1536w\" sizes=\"auto, (max-width: 1600px) 100vw, 1600px\" \/><figcaption class=\"wp-element-caption\">Weak vs strong alt text: five habits that separate them.<\/figcaption><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">Alt text for STEM images: examples by image type<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The table below shows the pattern for six image types we see in most science and math titles. Worked examples with full long descriptions follow it.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1600\" height=\"1004\" src=\"https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-examples-by-image-type.webp\" alt=\"Table of STEM alt text patterns by image type. For graphs, state graph type, variables and trend; long description covers axes, units and key points. Geometry: shape and given measures. Chemical structures: compound or group; atoms and bonds. Circuits: components and connections. Data tables as images: replace with a coded table. Lab photos: apparatus and purpose.\" class=\"wp-image-1270\" srcset=\"https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-examples-by-image-type.webp 1600w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-examples-by-image-type-300x188.webp 300w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-examples-by-image-type-1024x643.webp 1024w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-examples-by-image-type-768x482.webp 768w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-examples-by-image-type-1536x964.webp 1536w\" sizes=\"auto, (max-width: 1600px) 100vw, 1600px\" \/><figcaption class=\"wp-element-caption\">What the short alt states and what the long description covers, by image type.<\/figcaption><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">1. Line graph (physics)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Short alt:<\/strong> &#8220;Velocity-time graph of a cart that speeds up steadily for 4 seconds, then moves at a constant speed. Full description follows the figure.&#8221;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Long description:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Line graph. The horizontal axis is time in seconds, from 0 to 10. The vertical axis is velocity in meters per second, from 0 to 10.<\/li>\n\n\n\n<li>The line starts at the origin, (0, 0), and rises in a straight line to the point (4, 8).<\/li>\n\n\n\n<li>From (4, 8) the line is flat, staying at 8 meters per second until 10 seconds.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Note what the description leaves out. It does not calculate the acceleration. If the text or the exercise asks for it, working it out is the student&#8217;s job.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">2. Geometry diagram (assessment item)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Image description for math diagrams follows one rule above all: describe what is drawn and labeled, in a fixed order, and stop there.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Short alt:<\/strong> &#8220;Right triangle ABC with the right angle at C. Side AC is 6 centimeters, side BC is 8 centimeters, and side AB is labeled x.&#8221;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">That is complete. No long description is needed, because the short alt carries every given value. It does not say that x equals 10. A sighted student has to work that out, so a screen reader user must too.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">3. Chemical structure (organic chemistry)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Short alt:<\/strong> &#8220;Structural formula of ethanol, C2H5OH, described in detail below.&#8221;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Long description:<\/strong> &#8220;Two carbon atoms are joined by a single bond. The left carbon is bonded to three hydrogen atoms. The right carbon is bonded to two hydrogen atoms and one oxygen atom. The oxygen is bonded to one hydrogen atom, forming a hydroxyl group.&#8221;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If the question asks students to name the compound, drop &#8220;ethanol&#8221; from the alt text. Write &#8220;Structural formula of an unnamed compound&#8221; and keep the long description.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">4. Circuit diagram (electricity)<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Short alt:<\/strong> &#8220;Series circuit with a 9-volt battery, an open switch and two resistors. Description follows.&#8221;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Long description:<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Starting at the positive terminal of a 9-volt battery, a wire leads to a switch, shown open.<\/li>\n\n\n\n<li>From the switch, the wire leads to resistor R1, labeled 100 ohms.<\/li>\n\n\n\n<li>From R1, the wire leads to resistor R2, labeled 200 ohms.<\/li>\n\n\n\n<li>From R2, the wire returns to the negative terminal of the battery. There are no branches.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Tracing the loop from the source gives the reader a fixed path to follow. Spell out &#8220;ohms&#8221; and &#8220;volts&#8221; so screen readers do not skip or misread the symbols.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">5. Data table saved as an image<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The best fix is not alt text. Rebuild it as a real table with header cells, so readers can move cell by cell. If the image must stay for layout reasons, use a short alt such as &#8220;Boiling points of four alcohols. The same data appears in the table below&#8221; and place the coded table next to it.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">6. Photo of a lab setup<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Short alt:<\/strong> &#8220;Titration setup: a burette clamped above a conical flask that sits on a white tile.&#8221;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Long description, only if the procedure depends on it:<\/strong> &#8220;A burette is held upright by a clamp on a ring stand. Its tap is closed. Below the tap sits a conical flask containing a clear liquid. The flask rests on a white tile so color changes are easy to see.&#8221;<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Describe what is visible. Do not add the chemical names unless they appear on labels in the photo or in the caption.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How should you handle math and chemistry notation?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Code equations as MathML instead of images, so screen readers can voice them and readers can navigate them term by term. When an image of math must stay, write alt text that reads unambiguously aloud. For chemistry, spell out subscripts, charges and reaction arrows in words, and keep the voicing consistent across the whole title.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Math: MathML first, images as a fallback<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Good MathML accessibility starts with real markup, not pictures of equations. The DIAGRAM Center&#8217;s image description guidelines recommend rendering math in MathML. Reading software can then voice it in the style each reader prefers. The DAISY Knowledge Base calls MathML the best option now that browser support is widespread. It also notes that EPUB support depends on how current the reading system is.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For older reading systems, DAISY describes a fallback. Use an image of the equation with clear alt text and an extended description for complex equations. Keep the source MathML alongside. Two more cautions from the same guidance, as of October 2026:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Do not add the ARIA &#8220;math&#8221; role to MathML markup. It can make the math inaccessible.<\/li>\n\n\n\n<li>Do not rely on the MathML alttext attribute for descriptions. Reading system support for it is poor.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Voicing choices matter in teaching. The DIAGRAM guidance gives an example: a teacher may want students to hear &#8220;x superscript 2&#8221; rather than &#8220;x squared&#8221; to test whether they know the notation. Decide this per title and write it into your style sheet.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Chemistry: say it the way an expert would read it<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Formulas:<\/strong> write &#8220;C 6 H 12 O 6&#8221; or &#8220;C6H12O6&#8221; consistently, and test how your target screen reader voices it.<\/li>\n\n\n\n<li><strong>Arrows:<\/strong> replace symbols with words such as &#8220;reacts to form&#8221; or &#8220;is in equilibrium with&#8221;.<\/li>\n\n\n\n<li><strong>Charges and states:<\/strong> write &#8220;sodium ion, positive one charge&#8221; or &#8220;water, liquid&#8221; in full.<\/li>\n\n\n\n<li><strong>Conditions:<\/strong> state heat, light or catalysts in the order they appear on the arrow.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Long descriptions in EPUB<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">This is where many alt text projects break. The DAISY Knowledge Base states that the HTML longdesc attribute is not supported in EPUB. It calls a plain hyperlink to the description the most reliable method today. Adding aria-details to the image lets assistive technology offer the link right when the reader meets the figure.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>&lt;figure id=\"fig-4-2\"&gt;\n  &lt;img src=\"images\/fig-4-2.png\"\n       alt=\"Series circuit with a 9-volt battery, an open switch and two resistors. Description follows.\"\n       aria-details=\"fig-4-2-desc\"\/&gt;\n  &lt;figcaption&gt;Figure 4.2 A simple series circuit.\n    &lt;a id=\"fig-4-2-desc\" href=\"desc\/fig-4-2.xhtml\"&gt;Description of figure 4.2&lt;\/a&gt;\n  &lt;\/figcaption&gt;\n&lt;\/figure&gt;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Two more points for EPUB files. DAISY advises against aria-describedby for descriptions that contain lists or tables, because the structure is flattened into plain text. And W3C&#8217;s EPUB Accessibility 1.1 requires accessibility metadata in the package document, including accessibilityFeature. If every complex image has an extended description, the &#8220;longDescription&#8221; value tells readers and retailers so. Our guide to <a href=\"https:\/\/www.graveiens.com\/blog\/pdf-to-epub\/\">converting PDF titles to accessible EPUB<\/a> covers the rest of the file.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Workflow: SME writer to reviewer to QA<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Good STEM alt text and complex image descriptions come from a process, not from one talented writer. Here is the sequence we run, mapped to our four-stage quality process.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"1600\" height=\"600\" src=\"https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-workflow-sme-reviewer-qa.webp\" alt=\"Five-step STEM alt text workflow: triage images by type, subject expert writes short alt and long description, second subject expert reviews accuracy and answer leaks, client editors review against the style sheet, then QA tests markup, links, MathML and metadata in the delivery format.\" class=\"wp-image-1271\" srcset=\"https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-workflow-sme-reviewer-qa.webp 1600w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-workflow-sme-reviewer-qa-300x113.webp 300w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-workflow-sme-reviewer-qa-1024x384.webp 1024w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-workflow-sme-reviewer-qa-768x288.webp 768w, https:\/\/www.graveiens.com\/blog\/wp-content\/uploads\/2026\/10\/stem-alt-text-workflow-sme-reviewer-qa-1536x576.webp 1536w\" sizes=\"auto, (max-width: 1600px) 100vw, 1600px\" \/><figcaption class=\"wp-element-caption\">The five-step alt text workflow, from triage to tested delivery.<\/figcaption><\/figure>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Triage.<\/strong> Sort every image as decorative, simple, complex, math or assessment. This sets the effort for each one and flags quiz items early.<\/li>\n\n\n\n<li><strong>SME writes.<\/strong> A writer with the right subject background drafts the short alt and long description. They read the surrounding text first, so the description adds to the text instead of repeating it.<\/li>\n\n\n\n<li><strong>SME reviews.<\/strong> A second subject expert checks values, labels, terms, reading order and answer leaks. They also check consistency with earlier chapters.<\/li>\n\n\n\n<li><strong>Client review.<\/strong> Your editors approve the wording against your style sheet. Changes feed back into the style sheet, so later batches need fewer edits.<\/li>\n\n\n\n<li><strong>QA and delivery.<\/strong> We test the output in the target format. That includes empty alt on decorative images, working description links, valid MathML and correct accessibility metadata.<\/li>\n<\/ol>\n\n\n\n<p class=\"wp-block-paragraph\">A shared style sheet makes the biggest difference across large backlists. It records voicing rules for math, unit spelling, how to name figure parts and the TIDE order for each image type.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Can you use AI drafts safely?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Yes, as a first draft with a subject expert checking every output. A 2026 University of Pisa study compared human-written and LLM-generated alt text for STEM images. It found the AI text was fluent but had real gaps in formal meaning and structural detail. Never publish AI descriptions of assessment items or complex figures without expert review.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The study, by Cardia and colleagues, also found that common automated text metrics only partly catch accessibility errors. In other words, a draft can score well and still mislead a blind reader. That matches what reviewers see in practice.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Rules we follow when AI drafts are part of a project:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Draft, never final.<\/strong> Every AI draft goes through the same SME review as human drafts.<\/li>\n\n\n\n<li><strong>Check against the source.<\/strong> Reviewers compare every value, label and unit with the original figure. Invented data points are the most serious error.<\/li>\n\n\n\n<li><strong>Keep humans on assessments.<\/strong> Quiz and exam figures are written by subject experts from the start, because answer leaks are hard to spot in fluent text.<\/li>\n\n\n\n<li><strong>Protect unpublished content.<\/strong> Use tools only where your contract and data policy allow it. Ask before uploading manuscript images to any outside service.<\/li>\n\n\n\n<li><strong>Record what was AI-assisted.<\/strong> A simple log helps you answer questions from authors, partners or auditors later.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>See how your own figures come out. <a href=\"https:\/\/www.graveiens.com\/#contact\">Send 25 images for free sample alt text<\/a> and we will return short alt and long descriptions in your format.<\/strong><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What drives the cost of alt text writing services?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Cost depends on how complex your images are, not just how many there are. The main drivers are the share of images needing long descriptions, subject level and assessment content. Math conversion to MathML, source file quality, delivery format and turnaround also matter. Any quote should be based on a triaged sample of your real figures.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Use this table to prepare a request that vendors can scope accurately.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Cost driver<\/th><th>Why it changes effort<\/th><th>What to send for scoping<\/th><\/tr><\/thead><tbody><tr><td>Image mix<\/td><td>Complex figures with long descriptions take far longer than simple ones.<\/td><td>Image count by chapter and a sample set<\/td><\/tr><tr><td>Subject level<\/td><td>Advanced titles need writers and reviewers with deeper training.<\/td><td>Course level and discipline list<\/td><\/tr><tr><td>Assessment items<\/td><td>Answer-leak checks add a review step.<\/td><td>Which chapters contain quizzes or tests<\/td><\/tr><tr><td>Math and chemistry<\/td><td>Equation images may need MathML conversion as well as alt text.<\/td><td>Count of equation images and source files<\/td><\/tr><tr><td>Source quality<\/td><td>Scanned pages and missing captions slow down writers.<\/td><td>Native files, PDFs or scans<\/td><\/tr><tr><td>Delivery format<\/td><td>EPUB, HTML, tagged PDF and XML each need different markup and QA.<\/td><td>Target format and any platform specs<\/td><\/tr><tr><td>Style and review rounds<\/td><td>No style sheet means building one; more rounds mean more time.<\/td><td>Existing style guide and approval steps<\/td><\/tr><tr><td>Turnaround<\/td><td>Tight dates need more writers working in parallel.<\/td><td>Required delivery dates by batch<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">If you are working toward a public-sector deadline, plan backlist work early. As of October 2026, ADA.gov states that a Department of Justice interim final rule moved the first Title II web compliance date. Larger state and local governments now have until April 26, 2027. Our <a href=\"https:\/\/www.graveiens.com\/blog\/ada-title-ii-deadline\/\">ADA Title II deadline guide<\/a> explains what that means for education content.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Common mistakes and quality checks<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Most failed alt text audits come from a short list of habits. Check every batch for these before delivery:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Caption copies.<\/strong> Alt text that repeats the caption adds nothing. Describe what the caption does not.<\/li>\n\n\n\n<li><strong>&#8220;Image of&#8221; openers.<\/strong> Screen readers already announce an image. Start with the image type instead, such as &#8220;Bar graph&#8221; or &#8220;Structural formula&#8221;.<\/li>\n\n\n\n<li><strong>Facts the image does not show.<\/strong> The DAISY guidance warns against adding details a sighted reader could not see in the image.<\/li>\n\n\n\n<li><strong>Color-only meaning.<\/strong> If red and blue lines mean treated and control groups, say &#8220;treated group&#8221; and &#8220;control group&#8221;.<\/li>\n\n\n\n<li><strong>Answer leaks.<\/strong> Re-read every assessment description as if you were the student.<\/li>\n\n\n\n<li><strong>Broken description links.<\/strong> Test each link in at least one EPUB reading system and one screen reader before release.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How we write alt text for STEM images at GravEiens EduServices<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">GravEiens EduServices has worked with education publishers and institutions since 2017. We have served 350+ global clients with a team of 700+ experts and delivered more than 2 million digital assets. Our quality system is ISO 9001 certified.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Every alt text project runs through our four-stage QA: content creation, internal review, client review and final delivery. In practice, that means:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Writers and reviewers are matched to your subjects, from school science to higher education STEM.<\/li>\n\n\n\n<li>Short alt and long descriptions follow the TIDE pattern and your house style sheet.<\/li>\n\n\n\n<li>Equation images can be converted to MathML as part of our <a href=\"https:\/\/www.graveiens.com\/accessibility-remediation\/\">accessibility remediation services<\/a>.<\/li>\n\n\n\n<li>Descriptions are delivered inside the file, not as a spreadsheet you must merge, through our <a href=\"https:\/\/www.graveiens.com\/digital-epub-conversion\/\">EPUB conversion and digital publishing work<\/a>.<\/li>\n\n\n\n<li>Larger backlists can be bundled with editorial and production support through our <a href=\"https:\/\/www.graveiens.com\/publishing-solutions\/\">publishing solutions team<\/a>.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">For formats or platforms outside this list, we scope the work with you.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Frequently asked questions<\/h2>\n\n\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list \">\n<div id=\"faq-question-1760100000000\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">How long should alt text be for a STEM image?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Keep the alt attribute to one or two sentences. It should name the image type and state the main insight, so readers can decide whether to open the long description. Put values, labels and step-by-step detail in the long description. The DAISY Knowledge Base notes that readers must listen to the entire alt before moving on, so length has a real cost.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1760100000001\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">What is the difference between alt text and a long description?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Alt text is a short identifier stored in the image&#8217;s alt attribute. A long description is a fuller text version of the image&#8217;s essential information, kept in the page or a linked file. The W3C calls this a two-part text alternative for complex images: the short part identifies the image and points to the long part.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1760100000002\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Should alt text give the answer to a math or science question?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>No. In assessments, the description should state only what a sighted student is given: labels, values and shapes. If a triangle diagram asks students to find side x, the alt text names x but never its value. If a question asks students to identify a compound, do not name the compound in the alt text.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1760100000003\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Do equations need alt text if they are in MathML?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Native MathML usually needs no separate alt text, because screen readers voice the markup directly. The DAISY Knowledge Base advises against adding the ARIA math role to MathML. Alt text is needed when an equation is delivered as an image, for example as a fallback for older EPUB reading systems.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1760100000004\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">Can AI write alt text for STEM images?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>AI can produce a useful first draft, but not a final one. A 2026 comparative study of STEM images found that LLM descriptions were fluent yet missed formal meaning and structural detail. Treat AI output as a draft, have a subject expert check every value and label, and write assessment items by hand.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1760100000005\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">How do you add long descriptions to an EPUB?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>The most reliable method today is a hyperlink to the description, either in a separate file or at the end of the section. Add aria-details on the image so assistive technology can offer the link. The longdesc attribute is not supported in EPUB. Then declare longDescription in the accessibility metadata when every complex image has one.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1760100000006\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question \">How much do alt text writing services cost?<\/h3>\n<div class=\"rank-math-answer \">\n\n<p>Pricing depends on the image mix, subject level, share of assessment items, math conversion needs, source quality, delivery format and turnaround. A per-image figure means little until the images are triaged. The fastest route to an accurate quote is a sample batch of your real figures, scoped against your style and format needs.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<div class=\"wp-block-group cta-box\"><div class=\"wp-block-group__inner-container is-layout-flow wp-block-group-is-layout-flow\">\n<h2 class=\"wp-block-heading\">Get sample alt text for your STEM figures<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Send us 25 images from a current title: graphs, diagrams, structures or quiz figures. Our subject writers will return short alt text and long descriptions using the TIDE pattern, ready for your EPUB or web workflow.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.graveiens.com\/#contact\"><strong>Send 25 images for free sample alt text<\/strong><\/a><\/p>\n<\/div><\/div>\n\n\n\n<h2 class=\"wp-block-heading\">Sources<\/h2>\n\n\n\n<ol class=\"wp-block-list\">\n<li>W3C Web Accessibility Initiative, <a href=\"https:\/\/www.w3.org\/WAI\/tutorials\/images\/complex\/\" rel=\"noopener\" target=\"_blank\">Complex Images tutorial<\/a> (updated April 2026).<\/li>\n\n\n\n<li>DAISY Consortium, Accessible Publishing Knowledge Base, <a href=\"https:\/\/kb.daisy.org\/publishing\/docs\/html\/images-desc.html\" rel=\"noopener\" target=\"_blank\">Image Descriptions<\/a>; also its MathML and longDescription metadata pages.<\/li>\n\n\n\n<li>DIAGRAM Center (Benetech) and NCAM at WGBH, <a href=\"http:\/\/diagramcenter.org\/specific-guidelines-g.html\" rel=\"noopener\" target=\"_blank\">Image Description Guidelines: Mathematics<\/a>.<\/li>\n\n\n\n<li>Cardia, M., Angileri, L., Poggianti, C. and Leporini, B. (2026), <a href=\"https:\/\/arpi.unipi.it\/handle\/11568\/1365227\" rel=\"noopener\" target=\"_blank\">Human vs LLM-Generated Alt Text for STEM Image Accessibility: A Comparative Study<\/a>, University of Pisa.<\/li>\n\n\n\n<li>W3C, EPUB Accessibility 1.1, W3C Recommendation (package metadata requirements).<\/li>\n\n\n\n<li>U.S. Department of Justice, ADA.gov fact sheet on the Title II web and mobile accessibility rule, including the April 2026 interim final rule on compliance dates.<\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\">About the author<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>GravEiens EduServices Editorial Team.<\/strong> Our editorial team writes about accessible publishing, digital conversion and content development for K-12, higher education and professional publishers. The team draws on the subject experts, accessibility specialists and production staff who deliver GravEiens EduServices projects.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Alt text for STEM images, with short alt and long description examples for graphs, geometry, chemistry and circuits. Get 25 sample images described free.<\/p>\n","protected":false},"author":1,"featured_media":1268,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[180],"tags":[185,189,187,188,186],"class_list":["post-1272","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-accessibility","tag-alt-text","tag-epub-accessibility","tag-image-descriptions","tag-mathml","tag-stem-accessibility"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/posts\/1272","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/comments?post=1272"}],"version-history":[{"count":2,"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/posts\/1272\/revisions"}],"predecessor-version":[{"id":1294,"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/posts\/1272\/revisions\/1294"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/media\/1268"}],"wp:attachment":[{"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/media?parent=1272"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/categories?post=1272"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.graveiens.com\/blog\/wp-json\/wp\/v2\/tags?post=1272"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}