New TPT sellers regularly upload the same image as both, or put their sample pages in the thumbnail slots and wonder where the "download preview" button went. They're two different things with two different jobs. Here's the split, checked September 2026 against TPT's own help pages.
A thumbnail is a picture on your listing — buyers look at it. A preview is a downloadable sample of the resource itself — buyers open it. Thumbnails earn the click; the preview closes the sale.
| Rule | Detail |
|---|---|
| How many | up to 4 images per product |
| Size | at least 750×750px, square |
| File size | under 4MB each |
| Two ways to make them | let TPT auto-generate them from your product file, or upload your own |
Auto-generation is quick but takes the first pages of your file as-is; uploading your own lets you choose which pages show and add labels. If you upload your own, TPT suggests zoomed-out screenshots of your best pages — small but still legible.
| Rule | Detail |
|---|---|
| What it is | a demo-length version of the actual product, downloadable before buying |
| Length | any length — most sellers use 1–3 pages |
| File types | .pdf, .jpg, .jpeg, .png, .bmp, .tif, .tiff |
| Free resources | no preview upload at all — the full free file is the preview |
TPT's own seller tip is worth repeating: make the preview long enough to show what the resource does, without giving the content away. A worksheet pack might preview one complete worksheet of twelve; a unit plan might preview the overview page plus one lesson.
Putting sample pages only in thumbnails means buyers can't examine them closely — thumbnails display small, and squinting buyers don't buy. Putting your polished cover in the preview wastes the one slot buyers use to judge substance. And if you sell a free resource, stop looking for the preview upload — it isn't there on purpose.
Specs checked September 2026 against TPT's help centre ("What's the difference between a thumbnail and a preview?", "How do I generate thumbnails for my products?", "What file type can my product preview be?"); TPT can change them — their help centre is the authority. Not affiliated with TPT (Teachers Pay Teachers).