An image that looks perfectly sharp on a screen can print blurry or pixelated if it wasn’t sized with printing’s specific requirements in mind. Here’s the math and the process to get it right.
Why print and screen sizing are different
Screens display images using far fewer pixels per inch than a quality print requires. A photo that looks sharp filling your monitor at 96 pixels per inch would look visibly soft printed at the same pixel dimensions, because print typically needs around 300 pixels per inch to look sharp at close viewing distance.
The formula
To find the minimum pixel dimensions you need: multiply your desired print size in inches by 300 (a safe standard for sharp prints).
- 4 × 6 inch print: 1200 × 1800 pixels minimum
- 5 × 7 inch print: 1500 × 2100 pixels minimum
- 8 × 10 inch print: 2400 × 3000 pixels minimum
- Letter-size poster (8.5 × 11 in): 2550 × 3300 pixels minimum
What if your image is smaller than the target?
If your source image doesn’t meet the minimum pixel dimensions for your desired print size, you have two realistic options: print at a smaller physical size that the image does support, or upscale the image and accept some softness (see our guide on resizing without losing quality for what upscaling can and can’t do). There’s no way to print a genuinely low-resolution image large and have it look sharp.
Format matters less for print than for web
Unlike web images, file size isn’t usually a major concern for printing, so use PNG or a high-quality JPG (90–100 quality setting) to avoid any visible compression artifacts in the final print. Save file-size-conscious compression for images destined for screens, not paper.
A simple pre-print checklist
- Determine your desired physical print size.
- Multiply both dimensions by 300 to find your minimum required pixel dimensions.
- Confirm your source image meets or exceeds those pixel dimensions.
- Resize to the exact target pixel dimensions using a high quality setting (90+).
Once you know your target pixel dimensions, resizing to that exact size takes just a few clicks — no design software required.