Is the image alt text a Google ranking factor?

Published: November 28, 2018

Yes, according to official statements from Google (quoted below), the alt text is a ranking signal.

โ€œanchor text (and image alt text) helps us quite a bit in understanding context, so I wouldn’t leave it out if you can avoid it.โ€ source

โ€œAlt text is extremely helpful for Google Images — if you want your images to rank thereโ€ย source

Q: “Does the alt image tag play a role in rankings for non-image search? Should we be putting descriptive comments on what the pictures are to help with general search results”?

A: โ€œSo, the text in the alt attribute for image tags is seen as a part of the text on the page. So, that’s something where it does help us a little bit to understand that page better[โ€ฆ]. It does play a big role for image search though. So, if you have images that you want to have appear in Google images, then make sure that you have a clean alt text there. Also, make sure that you watch out for the other aspects that relate to image search, as well.โ€ย source