Full guide
Spec change log
Platforms change upload requirements quietly. Merch by Amazon dropped a rule that half the internet still teaches, and there was no announcement — the old wording simply became "previously required". This page is the record: what changed, when we found it, and where to check it yourself.
Confirmed changes
6 October 2026 — re-checked all four. No number changed. Printful migrated its help centre and the article we cite moved to a new address; the old link now returns Not Found. Every figure in it is unchanged — 200 MB, 20,000 × 20,000 px, 150 DPI for most apparel, PDF accepted but not advised, and the rule that a file name with two dots before the extension fails to upload. The link on this site now points at the new address. Printify revised its file-types article on 29 September; the formats, the 100 MB and 20 MB ceilings and the 300 DPI recommendation are all as they were. Redbubble's page has not been touched since 4 August. Merch by Amazon could not be re-checked: its Best Practices page sits behind a sign-in. Its verification date stays at 14 September rather than being quietly refreshed — a date you cannot stand behind is worse than an old one. 14 September 2026 — Merch by Amazon removed the exact-size requirement. For years artwork had to be exactly 4500 × 5400 pixels; one pixel off was a refusal. Amazon's Best Practices page now reads: product templates *previously* required specific artwork for each product type, and you are *no longer required to export or upload specific sizes*. The current design editor accepts anything above 485 × 485 and scales it to fit each product. Amazon gives no date for when this took effect, and made no announcement we can find. We confirmed it on 14 September 2026 by reading the page directly. The same page now asks you to trim the transparent margin rather than pad to a fixed canvas, because the editor centres artwork by measuring its own bounds — which inverts the advice that was correct under the old rule. What it means for you: a 4000 × 4800 design no longer needs rebuilding, and any checker still testing for an exact match will fail files Amazon would have accepted. 4500 × 5400 remains a sensible size to work at — it is 15 × 18 inches at 300 DPI — but it is now a default rather than a gate.
When each platform was last checked
A number is only as good as the date beside it. Verified is when we last read the platform's own page; document dated is when that page says it was last updated. Both matter: a document can sit unchanged for months, and so can our reading of it.
| Platform | Source document | Verified | Document dated |
|---|---|---|---|
| Printful | How should I prepare my print file for the best results? | 6 October 2026 | 6 October 2026 |
| Printify | What type of print files does Printify require? | 6 October 2026 | 29 September 2026 |
| Redbubble | Dimensions & Format | 6 October 2026 | 4 August 2026 |
| Merch by Amazon | Best Practices — Artwork tips (sign-in required) | 14 September 2026 | not published page carries no date |
| Etsy | Requirements and Best Practices for Images in Your Etsy Shop | 6 October 2026 | 6 October 2026 |
Where each number comes from
- Printful — How should I prepare my print file for the best results?
Verified 6 October 2026 · document dated 6 October 2026 - Printify — What type of print files does Printify require?
Verified 6 October 2026 · document dated 29 September 2026 - Redbubble — Dimensions & Format
Verified 6 October 2026 · document dated 4 August 2026 - Merch by Amazon — Best Practices — Artwork tips (sign-in required)
Verified 14 September 2026 - Etsy — Requirements and Best Practices for Images in Your Etsy Shop
Verified 6 October 2026 · document dated 6 October 2026
How this record is kept
Every number on this site lives in one file, with the source URL and the verification date attached to it. The machine-readable copy is published at [/specs.json](/specs.json) and carries the same dates, and the build refuses to ship if the two disagree. When a number changes, the change appears here with the wording that justified it — not a summary, the platform's own sentence. This is deliberate. Most published print-on-demand specifications are second-hand and undated, which is how a rule Amazon removed is still being taught. An undated number is not a fact, it is a rumour with a decimal point.
Check one file
No account, no email, nothing uploaded.
Choose a design fileFrequently asked questions
Found something we have wrong?
Please tell us — [email protected]. A link to the platform page carrying the current wording is all we need, and the correction goes up with the date it was made. Being corrected is cheaper than being quoted while wrong.
How often do you re-check?
Whenever a number is used in a decision that matters, and at minimum when someone reports a discrepancy. The verification dates above are honest — if a date is old, treat the number as old.
Why is there only one change listed?
Because this record starts in September 2026, and we will not backfill it with changes we did not verify ourselves. A log padded with second-hand entries would defeat its own purpose.