Walmart main image size: 2200x2200 and Sume's multiples of 16

Walmart's guidelines ask for a main image of 2200 x 2200 px, a file of 5 MB or less, in JPEG, JPG, PNG or BMP, on a seamless white background. On Sume, a custom image_size on openai/gpt-image-2.5 needs both edges to be multiples of 16, and 2200 is not (2200 / 16 = 137.5). Generate 2208 x 2208, then resize to 2200 x 2200 with your own image tool.

What does Walmart require?

From Walmart Marketplace Learn, page last updated May 12, 2026, read 2026-09-30.

Which sizes does Sume accept near 2200?

The Image API docs give four rules for a custom size: both edges multiples of 16, a maximum edge of 3840, aspect ratio at most 3:1, and 655,360 to 8,294,400 pixels. The nearest square sizes are 2192 x 2192 (4,804,864 px) and 2208 x 2208 (4,875,264 px). Both pass. The docs also say exact pixel targeting through target_pixels is not advertised by any model in v1, so do not plan on Sume doing the last resize.

What does the request look like?

Choose a JPEG for file size, and set the background to opaque. A white prompt does not guarantee exact 255 values, so sample the corners afterwards.

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": "Ceramic mug centered on a seamless pure white background, soft shadow, product photo",
    "image_size": "2208x2208",
    "background": "opaque",
    "output_format": "jpeg"
  }'

What do I still have to check?

Resize to exactly 2200 x 2200, confirm the file is 5 MB or less, and check that the background is the white Walmart asks for. Compare the picture with the real product before listing. For another marketplace's size rule, see the Shopify 2048 x 2048 post. Confirm current rules on Walmart's page before you upload.