Alt Text Checker
Reads your image description the way a screen reader will.
- 100% success
Tool input
Overview
About this tool
Checks one alt text against the character limit the network actually stores and against the nine accessibility rules people get wrong — the “image of” opener, the caption pasted in twice, the hashtags, the untranscribed quote card — and tells you which of them this description breaks.
Instructions
How to use it
Paste the description exactly as you typed it, pick the network and say what the image is doing. The last of those changes the rules completely, so it is worth getting right.
The limits are not the same anywhere
Instagram stores 100 characters, LinkedIn 120, X 1,000, Pinterest 500, Bluesky 2,000. A description written for one and pasted into another is cut in the middle of a sentence — and because alt text is invisible in the composer, nobody ever sees it happen.
The four roles
- Informative — describe what a sighted reader takes from it in a glance.
- Text in the image — every word in the graphic has to be here. For a listener this is the graphic.
- Chart — give the trend and the numbers, not the styling.
- Decorative — leave it blank so assistive technology skips it.
Questions
Frequently asked
How long can alt text be on Instagram?
Instagram’s custom alt text field takes 100 characters. It is the tightest limit of any network here, which is why a description written for X almost never fits.
Should alt text start with “image of”?
No. The screen reader announces that it is an image before it reads a word of your text, so the listener hears “image, image of a loaf”. Start with the subject.
Can I put hashtags in alt text?
You can, and it does nothing except make the description worse. Alt text is not searched, and every platform’s accessibility guidance names keyword stuffing in this field specifically.
What about a decorative image?
Leave the field empty. Describing a divider or a texture stops the listener to tell them about something that carries no meaning.
Does alt text help SEO?
On a web page it is one of the signals an image search can use. On a social network it is not indexed at all. Write it for the person listening either way.
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