Google Merchant Center image size: 500x500 minimum, 1500x1500 advised

Google Merchant Center lists at least 500 x 500 pixels for product images and recommends 1500x1500 pixels or above. 1500 is not a multiple of 16, so it is not a valid custom image_size on Sume's openai/gpt-image-2.5; 1536x1536 is, and it meets the recommendation.

What does Google list for size?

From the page read on 2026-09-30: at least 500 x 500 pixels, with 1500x1500 pixels or above recommended.

Why not request 1500x1500?

The Image API docs require both edges of a custom image_size to be multiples of 16. 1500 divided by 16 is 93.75, so it fails, and the next multiple up is 1504. 1536 is 96 x 16 and gives a square of 2,359,296 pixels, inside the 655,360 to 8,294,400 range.

What does the request look like?

Send image_size and a prompt that asks for the product alone.

curl -X POST https://api.sume.com/v1/images \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-image-2.5",
    "prompt": "Stainless steel water bottle, plain white background, product photo",
    "image_size": "1536x1536",
    "output_format": "png"
  }'

What are the limits of this answer?

Size is one of the requirements on Google's page and not the only one. It also lists content rules, so a correctly sized image can still be disapproved; see the other Merchant Center posts linked above. Pages change, so re-read Google's before you upload.