What are the optimal proportions for images used in Google Shopping data feeds?
Well, if you look at the images of products in Google Shopping, or images in the search results page, you will see that they are all square.
So if you want to maximize the area that your product images show up in Google Shopping results, think inside the box. Be a square.
The way I make product images for the datafeed is to make a new blank square image in Fireworks at 500px by 500px.
Then I take my optimized and color corrected full sized product images and drop them in the 500 x 500 Fireworks doc. I re-size the product image until the product uses the square space to best advantage.
Then I export the 500px image and save it in the folder I've set up for datafeed images.
Then I take the next full sized product image and drop it in the 500px datafeed image doc and size and position it, too, and export again.
I keep doing this until I have all the images I want to include in the datafeed all ready to go.
Maybe you've already made square images for your shopping cart, in which case, lucky you. Just link to those, as long as they are over 400px.