Let’s go through what successful alt text is. It is…
If alt text descriptions are too long it can unnecessarily burden people who use screen readers. As an approximate guideline, alt text should be under 100 words, but never less than 10. The average length of alt text is between 25 and 30 words long.
Alt text should reflect the purpose of the visual, in the context of the publications and journals focus. Remember, the alt text for the same image may vary dependent on the paper it is situated in, as the purpose of the research will be different.
You want to make sure that your alt text doesn’t repeat anything that is already in the surrounding text. If you struggle to think of anything unique to write for the alt text of an image, you should question whether the image should be identified as a decorative image. And then think about if the image is necessary in your research.
Spell out all contractions, numbers, and non-Latin letters and present the information in a logical and consistent order.
5. Plain text
Do not use formatting, such as bullet points, in your alt text. People who use screen readers cannot interact with alt text or access the formatting in the alt text. So, if formatting is used, this makes the alt text confusing.
You should make sure that your alt text is presented consistently in your research. Use the same style and level of language that is used in the main body of your research.
Successful alt text is inclusive. It should not contain additional information that a sighted person (or someone not using a screen reader) would miss.
Finally, make sure that your alt text is concluded with a full stop. Doing this allows screen reading software to pause, before it continues onto the next piece of text.