Files and limits
What you can upload to the AlternativeText Generator, and the limits that apply.
Images
| Item | Limit |
|---|---|
| Formats | JPEG/JPG, PNG, WebP |
| Size per image | 5 MB |
| Dimensions | In the focused workspace, images whose longest edge exceeds 4096 pixels are scaled down automatically before analysis |
PDFs
| Item | Limit |
|---|---|
| Size | 50 MB |
| Page preview | Pages are shown three at a time. This is only how previews are displayed — it is not a limit on the number of pages you can review. |
Batches
| Item | Limit |
|---|---|
| Batch upload (desktop) | Up to 50 images at once; a notice appears above 25 |
| Batch upload (mobile) | Up to 10 images at once; a notice appears above 8 |
| Analysis speed | Up to 4 images are analyzed at a time, automatically — there is nothing to configure |
Result text
| Item | Guidance |
|---|---|
| Short alt text length | 120 characters ideal · 180 acceptable · 250 hard limit. These are AlternativeText's guidelines, not WCAG requirements. |