Describe meaningful product image information
Describe what the buyer needs from an informative image, not every visual detail. For a functional image, explain its action. Pure decoration generally uses an empty alternative so assistive technology can skip it. A complex chart needs its information available in usable text or a table, not squeezed into a vague image description.
Illustrative product page: a size-chart image contains chest and sleeve measurements. Give the image a concise label and reproduce the actual measurements as an accessible table beside it. A violet divider below the chart contributes no product information and receives an empty alt value. The two images should not both be labeled “shirt size image” simply because they appear in the same section.
Leave decorative imagery out of the reading sequence
Alt text alone does not make an image-based size guide usable. Reading order, table headings, zoom behavior and contrast still matter. Repeating product keywords instead of describing the image’s purpose makes the alternative less helpful.
Next, review one buying task with images unavailable. Check whether the customer can still obtain the measurements, understand each control and complete the selection. Use the W3C image-purpose guidance when deciding the appropriate alternative.
Website field guide · Website usability checklist for a buying journey · Website accessibility
Reference: W3C WAI: images tutorial. Checked November 4, 2026.