Google Business Profile Post size: 1200 x 900 pixels.

Google's photo and video guidelines for Business Profiles cover post images too: JPG or PNG between 10 KB and 5 MB, a minimum of 250 by 250 pixels and a recommended 720 by 720. Google publishes no post-specific size. In practice the post card renders the image at 4:3, and 1200 by 900 pixels is the common export that fills that card at good quality while staying well inside the 5 MB cap.

The same file is drawn in more than 1 place. The post card on the profile is 4:3, the strip of recent posts on a search result uses a square thumbnail cut from the center, and the opened post shows the whole image. Design so the subject survives the square, and both surfaces keep it.

Portrait uploads are the usual mistake. A 4:5 social graphic loses more than a third of its height in the 4:3 card, and Google's guidelines ask for photos that are in focus and well lit with no significant alterations or heavy filters, so a poster that is mostly type tends not to be shown at all. Use a photograph of the product, the premises or the team with a short line over it, and export a separate landscape version. Video is accepted up to 30 seconds, 75 MB and 720p.