Printing
Upscale an image to poster size
To enlarge a photo for a poster, multiply the paper dimensions in inches by the pixel density your printer recommends, then choose the smallest upscale that reaches that target. Posters viewed from farther away may need fewer pixels per inch than handheld prints. If the largest supported scale falls short, choose a smaller poster or find the original.
Tested settings and honest limits
We used Upscale 8× on the 480 × 320 landscape, obtaining 3840 × 2560 pixels. At 150 PPI it covers 25.6 × 17.07 inches before cropping. For a 24 × 36 inch poster at that density you need 5400 × 3600 pixels, so this source remains short even after 8×. Choose a smaller poster or a larger original.
This ridge looks more defined than the ordinary resize, but the added snow texture is plausible. The saved deployment runs showed localized texture changes and differences between repeats. This single crop is not a guarantee that another run or every part of your poster will look the same.
This is a screen comparison, not a physical print test. Use Upscale 8× only when the calculated pixel target calls for it, inspect the complete result, and ask your printer for a proof. Repeated upscaling cannot create a record of lost scene detail.
Read how we test and where our evidence stops. These are saved engine outputs, cropped for the web without retouching.
How it works
- 1
Pick size and DPI
150 DPI for posters seen from a distance, 200 to 300 for close viewing.
- 2
Upscale 4× or 8×
Upload the original, not a chat or social copy. Enhance it first if it is grainy or blocky.
- 3
Crop and preview from a distance
Crop to the poster's shape and judge the result at 50 % zoom before ordering.
Why posters need less DPI than photo prints
The 300 DPI rule assumes someone holds the print at arm's length. A poster on a wall is usually seen from a metre or more away, and at that distance the eye cannot tell 300 pixels per inch from 150. Print shops commonly accept 150 DPI for posters. 200 DPI gives a margin for posters people will walk up to.
This matters because the numbers grow fast. A 24 x 36 inch poster at 300 DPI needs 7200 x 10800 pixels, about 78 megapixels. At 150 DPI it needs 3600 x 5400 pixels, about 19 megapixels.
Poster sizes in pixels
The table lists the exact pixels for each size at 150 and 300 DPI, plus the smallest source that reaches 150 DPI with one 4× or one 8× upscale. Metric sizes are converted from millimetres and rounded to the nearest pixel. For smaller prints, see the full print size chart.
Choosing 4× or 8×
Upscale 4× accepts photos up to 5 MP and makes them four times wider and taller. Upscale 8× accepts photos up to 1.25 MP, makes them eight times wider and taller, and uses 2 credits. Both give results up to 80 MP.
So a 1800 x 2700 photo (4.9 MP) reaches 24 x 36 inches at 300 DPI with Upscale 4×, and a 900 x 1350 photo (1.2 MP) reaches the same size with Upscale 8×. For 150 DPI you need only half those dimensions. Pick the smallest factor that reaches your target; reaching it with less enlargement keeps more of the result true to the original.
What kind of source photo works for a poster
A modern phone photo, straight from the phone that took it, often has enough pixels for an 18 x 24 inch poster at 150 DPI without any upscaling. The problem is usually the copy: a photo shared through a chat app, downloaded from social media or cropped hard may be only 1000 to 2000 pixels wide. Look for the original before you upscale a copy.
The upscalers are built for photos of nature, people, places and objects, so landscapes, cityscapes and well-lit portraits work well. Small text in the photo, such as signs in the distance, stays as soft as in the original. Photos with heavy grain or compression blocks should go through Enhance first, at the same size.
Step by step
Decide the poster size and viewing distance: 150 DPI for distance viewing, 200 to 300 for close viewing. Look up the target and compare it with your photo's pixel size.
If the photo shows grain or blocks at 100 % zoom, run Enhance first. Then run Upscale 4× or 8× on the clean copy. Crop the result to the poster's shape: 24 x 36 and 12 x 18 are 2:3, 18 x 24 is 3:4, 16 x 20 is 4:5, and A sizes are about 1:1.41.
Before ordering, view the file at 50 % zoom on a large screen and step back. That is closer to how the poster will be seen than checking every pixel at 100 %.
When to choose a smaller poster
If your photo is smaller than the 8× source column for the size you want, one upscale will not reach 150 DPI. Running the upscaler again on its own output adds pixels but not real detail. A smaller poster from the same photo will look better.
Faces need special care. A face that is only 40 or 50 pixels wide in the original stays soft when enlarged. PhotoRescue does not swap in a generated face, because it would not be the person in the photo.
Upload limits and the watermark
Free uploads can be up to 3 MB and 8 MP, and results are watermarked, so use the free plan to test the look. Paid plans accept up to 20 MB and 30 MP per upload and remove the watermark. Pro is $9.99 a month for 200 credits; Pro+ is $19.99 a month for 500. Upscale 8× uses 2 credits per photo.
Pixels for poster sizes at 150 and 300 DPI (inches x DPI; mm / 25.4 x DPI, rounded), and the smallest source that reaches 150 DPI with one 4× or 8× upscale (target / 4 or / 8, rounded up)
| Poster size | Pixels at 150 DPI | Pixels at 300 DPI | Smallest source for 4× at 150 DPI | Smallest source for 8× at 150 DPI |
|---|---|---|---|---|
| 11 x 14 in | 1650 x 2100 | 3300 x 4200 | 413 x 525 | 207 x 263 |
| 12 x 18 in | 1800 x 2700 | 3600 x 5400 | 450 x 675 | 225 x 338 |
| 16 x 20 in | 2400 x 3000 | 4800 x 6000 | 600 x 750 | 300 x 375 |
| 18 x 24 in | 2700 x 3600 | 5400 x 7200 | 675 x 900 | 338 x 450 |
| 24 x 36 in | 3600 x 5400 | 7200 x 10800 | 900 x 1350 | 450 x 675 |
| A3 (297 x 420 mm) | 1754 x 2480 | 3508 x 4961 | 439 x 620 | 220 x 310 |
| A2 (420 x 594 mm) | 2480 x 3508 | 4961 x 7016 | 620 x 877 | 310 x 439 |
| A1 (594 x 841 mm) | 3508 x 4967 | 7016 x 9933 | 877 x 1242 | 439 x 621 |
What it won't do
- It cannot turn a thumbnail into a poster that looks like a native high-resolution photo.
- It does not generate new faces, and small text stays as soft as in the original.
- It does not fix strong motion blur, missed focus, scratches or tears.
- Upscale 4× accepts photos up to 5 MP and Upscale 8× up to 1.25 MP; results are up to 80 MP.
- Free results are watermarked; use a paid plan for poster files.
Questions
How many pixels do I need for a 24 x 36 poster?
3600 x 5400 pixels at 150 DPI, which is fine from a distance, or 7200 x 10800 pixels at 300 DPI.
What resolution is good for an 18 x 24 poster?
2700 x 3600 pixels at 150 DPI. At 300 DPI it needs 5400 x 7200 pixels.
How many pixels is an A2 poster?
2480 x 3508 pixels at 150 DPI and 4961 x 7016 pixels at 300 DPI.
Can I make a poster from a phone photo?
Usually yes. The original file from a recent phone often reaches 150 DPI for 18 x 24 inches on its own. Upscale 4× or 8× helps when you only have a smaller copy.
Can I upscale a result again for a bigger poster?
A second run adds pixels, not a record of missing detail. The published example still falls short of the larger poster target after the first enlargement. A larger original or smaller poster is preferable.
Processing photos in bulk or inside your own app? Use the image enhancement and upscaling API