Shopify image limit 20 MB / 25 MP vs GPT Image custom sizes on Sume

A custom-size GPT Image render on Sume can never exceed Shopify's 25 megapixel limit, because Sume caps the output at 8,294,400 pixels (about 8.3 MP) with a longest edge of 3840. The limit that can still bite is Shopify's 20 MB file size, so choose the output format and quality with that in mind.

The two sets of limits

Shopify's limits are from its file upload help page (read 2026-10-08); the Sume limits are from the Images docs.

Arithmetic

3840 x 2160 = 8,294,400, which is exactly the Sume maximum and about one third of Shopify's 25 MP (8.29 / 25 = 0.33). A square 2880 x 2880 is also 8,294,400. A request for 1920 x 1088 is allowed since both edges divide by 16 (1920 = 120 x 16, 1088 = 68 x 16), whereas 1920 x 1080 is not, because 1080 is not a multiple of 16.

• Pick the edges from multiples of 16.
• Request the lowest pixel count that your storefront theme needs; Shopify serves resized copies.

Keeping under 20 MB

Large photographic PNGs are the ones that can pass 20 MB. If a render does, set output_format to jpeg or webp, lower the pixel count, or run a compression pass before upload. Test one SKU before you batch a catalog; see Images for the parameters.

Practical sizes

For product photography, 2048 x 2048 (4,194,304 px) is within Sume's 655,360 to 8,294,400 range and a multiple of 16 on both edges (2048 = 128 x 16). It is about 4.2 MP, a sixth of Shopify's 25 MP ceiling. A 3:1 banner such as 3840 x 1280 is also allowed, since the maximum aspect ratio is 3:1 and both edges are multiples of 16 (1280 = 80 x 16).

Use the post-step only when you need exact pixels: the docs describe a documented post-step through job target_pixels for models that do not take custom sizes.

• 2048 x 2048 = 4,194,304 px: allowed.
• 3840 x 1280 = 4,915,200 px: allowed, aspect exactly 3:1.
• 4000 x 2000: not allowed, the edge exceeds 3840.

Before you scale

Shopify's page also says images can be JPEG, PNG, WEBP, HEIC or GIF. Sume's image output_format covers png, jpeg and webp, so the overlap is three formats. For a catalog upload, pick one format and keep it consistent so that product pages load predictably. The page was read on 2026-10-08, and Shopify can change limits, so re-check before a large upload.