PPI calculator
Work out an image's pixel density (PPI) when printed or displayed at a given diagonal size — a quick way to check if an image has enough resolution for a specific frame or display size.
Result
Pixel density
How to use this calculator
- Enter the image's pixel width and height.
- Enter the diagonal size you're printing or displaying it at.
- Read the resulting pixel density.
Assumptions
- Treats the image/frame as a perfect rectangle.
Technical details: what the fields mean
- Image width
widthPx - The image's width in pixels.
- Image height
heightPx - The image's height in pixels.
- Print/display diagonal
diagonalInches - The diagonal size of the print or display you're targeting.
Methodology
Diagonal resolution (px) = √(width² + height²). PPI = diagonal resolution ÷ diagonal size in inches.
Worked example
3000×2000px image at a 20-inch diagonal
Inputs: widthPx=3000, heightPx=2000, diagonalInches=20
Result: 180 PPI
Practical guidance
- Above roughly 200–300 PPI, most people can't distinguish further quality improvements at normal viewing distance.
Common mistakes
- Comparing PPI figures across very different viewing distances (a phone held close vs. a poster viewed from across a room) as if they needed the same density to look equally sharp.
FAQs
What PPI do I need for a sharp print?
200–300 PPI is a common target for close-up viewing; large prints or posters viewed from a distance can look sharp at a much lower PPI.