Social Security Administration Guide: Alternate Text for Images

Text that is too long, verbose, wordy, replete in longness, just too much etc.

Alt text is spoken as one unit or chunk of text by the screen reader. The only way to repeat a portion of the text is to replay the whole text. This can make chart interpretation cumbersome and error-prone for screen reader users.

There are no specific limits on text length for alternate text. However, a good rule of thumb is a few sentences or about 160 characters.

“Line chart showing average monthly dog treat distribution. For FY 2010, Pastel and other guide dogs, receive around 15 treats per month, with seasonal fluctuations. There is a peak in December of 18 treats for Pastel and 20 treats for other guide dogs. Other assistance dogs received an unfairly high distribution at 19 treats per month, with a massive 25 treats in December. The New Deal Plan calls for Pastel’s monthly average to climb steadily throughout FY 2011 from 15 to 30. Other Guide dogs will see a corresponding decline in treats, from 15 in October down to a steady 5 per month by May. Other service dogs will see a slight initial raise in their average treat intake from 20 to 21 by December, only to experience a retribution-style drop in treat benefits of a paltry 1 treat per month beginning in February.”
It’s too long. Besides the repetition of the caption text, there is too much information to be easily read in the alt-text.

alt-text = “” (null)
It’s now redundant. The detail in the main text is probably useful for all readers, since it explains the major points of the plan. Note that in moving the reference to Figure 20 after the various explanations of the data reinforces to the reader that the figure is redundant, and therefore null alt-text is acceptable.