Walmart image file names: GTIN-14 and 100x100 swatches in a batch
Walmart recommends the 14-digit GTIN in each image file name and lists swatches at 100x100 px. How to name and size a batch of generated images to match.
Walmart recommends putting the 14-digit GTIN in each image file name, and its guide lists swatch images at 100 x 100 px (read 2026-10-02). Sume returns generated images under its own media URLs, so you rename on download: keep one table of GTIN, shot name and job id, and let that table decide every file name.
The two rules
Both come from Walmart's image guidelines (read 2026-10-02). The GTIN is a recommendation, not a stated rejection reason, so treat it as housekeeping that makes support cases and re-uploads easier.
| Item | What the page says |
|---|---|
| File name | Use the 14-digit GTIN in the file name (recommended) |
| Swatch images | 100px x 100px |
| Main image size | 2200px x 2200px; 1500px x 1500px minimum for zoom |
| File size | 5MB or less |
Keep the mapping outside the file
Sume does not name your files. An image result gives you a job id and a Sume media URL such as https://media.sume.com/img/01J.../0.png. Pass your GTIN in the job metadata field, which the Image API stores on the job and does not send to the provider (Image API).
Pad the GTIN to 14 digits yourself. A 12-digit UPC becomes 00 plus the UPC, and a 13-digit EAN becomes 0 plus the EAN. Then name the main file <GTIN14>_main.jpg, the next <GTIN14>_2.jpg, and so on.
Swatches are a post-step
A swatch is a 100 x 100 crop of the colour or material. Generate it at a normal size from the same reference photo, then downscale in your own pipeline. Do not ask the model for 100 x 100 pixels: the docs say custom GPT sizes need both edges as multiples of 16 and a minimum of 655,360 pixels, so that size is below what the endpoint accepts.
Why bother with the naming
When a listing is flagged or an image needs replacing, a file called with the GTIN tells you at once which item it belongs to. Without it, someone has to open each image and match it by eye. In a catalogue of hundreds of SKUs that is the difference between a one-minute fix and an afternoon.
Keep the mapping table under version control and regenerate file names from it, not by hand, so a re-run produces the same names.
A batch plan
Names are hard to change once files are in a feed, so name them before upload.
- One job per SKU and shot, each with its own
Idempotency-Key, so a retry cannot bill twice (Jobs and results). - GTIN and shot name in
metadata; read both back when the job completes. - Download, rename, resize and re-check the 5 MB cap before the feed step.
- If your batch is an agent Format, a bulk run queues up to 100 items with a concurrency window of 1 to 16.
Sources
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Written by Sume