How many pixels does an AI print need? 300 per inch, and at 16x20 our PNG is over Etsy's download limit
On this page
The usual answer is 300 pixels per inch of print: 2400 x 3000 for an 8x10, 4800 x 6000 for a 16x20, 7200 x 10800 for a 24x36. A square Midjourney 8.2 HD image is 2048 x 2048 and a square Gemini 4K image is 4096 x 4096, so neither reaches a 16x20 at that rate without more pixels. (Shops write DPI. Here it means pixels per inch of print.)
From a 4K Gemini picture we made 16x20 files of 4800 x 6000 pixels: the PNG is 35.8 MB, over Etsy's 20 MB per file for digital downloads, and the JPEG is 3.6 MB.
How many pixels does each print size need?
Multiply the print's width and height in inches by 300. The last two columns give the pixels per inch a square image has once it's cropped to the print's shape: its side divided by the print's long edge.
| Print size | Pixels at 300 DPI | Megapixels | From a 4096 px square | From a 2048 px square |
|---|---|---|---|---|
| 8x10 in | 2400 x 3000 | 7.2 | 410 | 205 |
| 16x20 in | 4800 x 6000 | 28.8 | 205 | 102 |
| 18x24 in | 5400 x 7200 | 38.9 | 171 | 85 |
| 24x36 in | 7200 x 10800 | 77.8 | 114 | 57 |
Midjourney's page says version 8.2 makes square images of 2048 x 2048 pixels in HD and 1024 x 1024 in SD. The HD size is 6.8 inches at 300 DPI, and "some posters can be printed at 150 DPI and still look clear because they are viewed from further away." Printify recommends 300 DPI and names 120 to 150 for large items such as leggings, blankets and tapestries. Printful asks for 150 to 300 depending on the product.
A 4096 px square gives 205 at 16x20, under the 300 Printify recommends and inside Printful's range. At 24x36 it gives 114, under the 120 Printify names for large items and under Printful's 150. Gemini can also make 4K images in the print's own shape: Google's page lists 3712 x 4608 for 4:5, 3584 x 4800 for 3:4 and 3392 x 5056 for 2:3, which is 230, 199 and 140 at 16x20, 18x24 and 24x36. Each product page gives its own requirement, so check it before you decide.
The DPI number inside a file changes none of this. The Gemini JPEGs we used say 300 DPI in their header and are 4096 pixels wide, which is 13.7 inches at 300. Changing the DPI of a photo changed neither its size nor a pixel in our earlier test, and Redbubble says "DPI and PPI don't affect your final uploaded image."
What do Etsy, Printify, Printful and Redbubble accept?
We read each shop's help page on 2 November 2026.
| Shop | File types | Largest file | Largest size in pixels |
|---|---|---|---|
| Etsy, digital downloads | JPG, PNG, PDF, GIF, ZIP and others | 20 MB, five files | not stated |
| Printify | JPEG, PNG, SVG | 100 MB for JPEG and PNG | not stated |
| Printful | PNG or JPEG, PDF accepted | 200 MB | 20,000 x 20,000 |
| Redbubble | JPEG and PNG | 300 MB | 13,500 x 13,500 |
None of the four pages lists WebP or AVIF. Etsy's 20 MB is for the digital files you attach to a listing. Printify and Printful each give their own limits for the print files you upload to them.
A 24x36 at 300 DPI is 7200 x 10800 pixels, inside every pixel limit in the table. Redbubble also lists minimums by product: art prints need 3840 x 3840 pixels, which "cover all sizes up to extra large". A 4096 px Gemini square clears that and a 2048 px Midjourney image doesn't, but Redbubble's posters need 2870 x 4100 pixels at extra small and 8310 x 11790 at large, more than a 4096 px square has. Printify says it will "automatically enhance the quality" of a low-resolution file before printing, and still recommends high-resolution designs.
At 16x20, the PNG is over Etsy's 20 MB and the JPEG isn't
We cropped two 4096 x 4096 Gemini images to each print's shape, resampled them to the pixels above, and saved each as a PNG and as a JPEG at quality 90. One is a generated harbour scene in a photographic style, which we call the photo, the other a flat illustration of a bakery. Sizes are in MB of 1,000,000 bytes.
| Print size | Photo PNG | Photo JPEG | Flat PNG | Flat JPEG |
|---|---|---|---|---|
| 8x10 | 11.3 | 1.4 | 7.2 | 0.7 |
| 16x20 | 35.8 | 3.6 | 24.0 | 1.7 |
| 18x24 | 43.9 | 4.3 | 29.7 | 2.0 |
| 24x36 | 70.6 | 6.5 | 48.8 | 3.3 |
The PNG passes 20 MB at 16x20 for both pictures. Every JPEG stays under it, and the largest, the 24x36 photo, is 6.5 MB. Against its PNG, the 16x20 JPEG scored 84.3 on the photo and 82.3 on the illustration in SSIMULACRA 2, where 80 means distortion that isn't noticeable side by side. In our PNG post, a photograph's PNG cost 5.7 to 9.3 times its JPEG at quality 90 through zopflipng. Ours, with default PNG settings, cost 8 to 11 times.
The unresized 4096 px photo is 24.5 MB as a PNG and 12.1 MB as the JPEG Gemini sent at quality 100, the size we measured for Gemini's Nano Banana 2. These files were resampled, not upscaled by an AI model, so they hold no new detail, and the sizes are for resampled files. A file from an AI upscaler may weigh differently. We didn't run one and we didn't print anything.
What Iminify does with a print-size file
These are 16x20 files unless noted, run through Iminify's API on 2 November 2026 at Smart, its default level, or at Lossless where the table says so. The score is SSIMULACRA 2 against the file we uploaded.
| Upload | Iminify setting | What came back | Score |
|---|---|---|---|
| JPEG, 3.59 MB | Smart | JPEG, 1.96 MB | 77.7 |
| JPEG, 18x24, 4.26 MB | Smart | JPEG, 4.25 MB | not scored |
| JPEG, 3.59 MB | Smart, size limit 1,500 KB | JPEG, 1.50 MB | 69.3 |
| JPEG, 3.59 MB | Smart, size limit 800 KB | JPEG, 0.68 MB, 2836 x 3545 | not scored |
| PNG, 35.80 MB | Lossless | PNG, 35.37 MB | not scored |
| PNG, 35.80 MB | Smart | PNG, 13.96 MB | 64.8 |
| PNG, 35.80 MB | Smart, size limit 19,000 KB | WebP, 2.59 MB | 79.8 |
| PNG, 35.80 MB | Smart, size limit 19,000 KB, JPG | JPEG, 2.30 MB | 79.0 |
| PNG, 35.80 MB | Lossless, size limit 19,000 KB | WebP, 1.53 MB | 70.2 |
| PNG, 35.80 MB | Lossless, size limit 19,000 KB, JPG | JPEG, 11.81 MB | 89.1 |
Smart on the JPEG scored 77.7, below the 80 at which distortion isn't noticeable. Smart reduces a PNG to a palette of at most 256 colours, and this one scored 64.8, against the 70 where artefacts are perceptible but not annoying. With a size limit on the PNG, Iminify returned a WebP at both levels, a format Etsy's list lacks, until we asked for JPG. A limit that quality can't reach shrinks the pixels: 800 KB left 2836 x 3545, or 177 DPI at 16x20. Iminify's docs say Smart searches for a quality only up to 36 megapixels. The 18x24 is past that and barely changed.
A 24x36 at 300 DPI is 77.8 megapixels, and Iminify refused it with "the largest this tool can process is 64 megapixels". The 35.8 MB PNG is over a free account's 32 MB, and Pro takes 90 MB (pricing, 2 November 2026).
What to do with a 4K AI image
- Work out the pixels: the print's inches times 300, or times 150 for a large item where the shop's page allows it (Printify names 120 to 150).
- Compare them with the image you have. A 4096 px square gives 205 DPI at 16x20 and 114 at 24x36. If it falls short, Midjourney's page points to "third party upscaling tools". We tested none.
- Save a JPEG at quality 90, as ours were, unless the art needs transparency, and check its size against the shop's limit. A PNG over Etsy's limit is the case in the table: Iminify at Smart with a 19,000 KB size limit and JPG chosen returned a 2.30 MB JPEG in our API run, and Iminify's PNG page has the same Size limit setting.
- Keep the file under 64 megapixels if you want Iminify to compress it, and under 36 if you want Smart to search for a quality. A 24x36 at 150 DPI is 19.4 megapixels.
How we measured this
The sources are flash-1x1-4K-photo-r1.jpg and flash-1x1-4K-flat-r1.jpg from Google's Nano Banana 2 (gemini-3.1-flash-image), generated for our Nano Banana post. Google's page now calls that model the previous generation and recommends Nano Banana 2.1, which we didn't measure; its 4K sizes there are the same. ImageMagick 7.1.1-43 cropped each square to 4:5, 3:4 or 2:3, resampled it with Lanczos, stripped its metadata and wrote the PNG with default settings. cjpegli from jpegli saved the JPEG from the PNG's pixels at quality 90 with 4:2:0 chroma. SSIMULACRA 2 is libjxl 0.12.0's, run on a PNG directly and on a JPEG or WebP after libjpeg-turbo's djpeg or libwebp's dwebp decoded it. We scored the 16x20 files and the Iminify rows that show a score.
