Instacart 3200x800 and 3200x400 banners: what Sume can make

Instacart display ads need four banners: a 3200x800 (4:1) mobile banner and a 3200x400 (8:1) desktop banner, each with and without a call to action, as JPG or PNG of at most 2.5 MB. Sume's docs list 4:1 and 8:1 among the normalized aspect_ratio values, but v1 has no explicit-pixel size, so you generate the ratio and make the exact 3200 px width in your own tool.

Instacart facts are from its display creative page, read 2026-10-01. Sume facts are from the Images API docs.

What are the four banners?

What can Sume do here?

Ask for the ratio, not the pixels. Whether a given model accepts 4:1 or 8:1 is per model, so read supported_parameters from GET /v1/images/models first. A custom image_size on openai/gpt-image-2.5 is capped at a 3:1 aspect and needs both edges to be multiples of 16, so it cannot make 4:1 either. Sume's docs say exact pixel counts are a post-step.

curl -X POST "https://api.sume.com/v1/images" \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "google/nano-banana-2",
    "prompt": "Wide pantry shelf banner with pasta, olive oil and tomatoes, empty space on the right, no text",
    "aspect_ratio": "4:1",
    "output_format": "png"
  }'

What do I do after it comes back?

Scale the image to 3200 px wide, keep the file at 2.5 MB or less, and add the call to action as live text in your design tool so you can export both versions. Instacart also asks for text of at least 15 px, so leave a clear area in the picture instead of asking the model to draw words. Confirm current rules on Instacart's page. For other ad sizes see resize an image for ad sizes.