Developer Tools
Pixel Density Calculator
Pixel Density: it computes pixel density as PPI = √(width² + height²) in pixels ÷ the diagonal in inches. Worked through below with real figures, and the calculator repeats the working on your own inputs — free, on-device, instant.
Pixel Density Calculator turns your horizontal resolution, vertical resolution and diagonal size into the pixel density in PPI using resolution and diagonal. The maths runs locally, so nothing you enter leaves the page.
Browser-side developer and utility helpers for everyday and learning use. Everything runs locally in your browser and nothing you enter is uploaded. Validate production or security-critical output with trusted, official tools before relying on it.
About this tool
Pixel Density is easiest to get wrong in the setup, not the arithmetic. It computes pixel density as PPI = √(width² + height²) in pixels ÷ the diagonal in inches. It matters when a format, encoding or size has to be exactly right for the system reading it. The worked example on this page (A 6.1-inch phone at 2532 × 1170 has diagonal 2,789.25 px, so PPI = 457.25 ÷ ... ≈ 457.25 PPI .) shows the full substitution; the calculator above runs the same working on your own numbers, in your browser, with nothing uploaded.
How to use
- Enter the horizontal resolution in pixels.
- Enter the vertical resolution in pixels.
- Enter the display diagonal in inches.
- Run the calculator to read the PPI.
Why use the Pixel Density Calculator
Instant
Each result is computed on your device the moment you run the tool.
Private
The text and numbers you enter stay in your browser and are never uploaded.
Free
No signup and no paywall to use any tool in this set.
Works offline
Once the page has loaded it keeps working on a weak or dropped connection.
Built for developers
Plain inputs and outputs you can copy straight into code, configs, or notes.
Honest by design
Conversions and heuristics are for everyday and learning use; verify security-critical output with trusted, official tools.
Common uses
Use it when working out a screen's pixel density
Use it when picking a phone or laptop by sharpness
Use it for image and video resolution work
Use it for everyday pixel-density reference
Use it when comparing two displays' sharpness
Use it when comparing pixel density across sizes
Technical notes
Pixel Density Calculator computes pixel density as PPI = √(width² + height²) in pixels ÷ the diagonal in inches.
Results are reference values; validate against your own environment before relying on them in production.
Nothing you type is uploaded — the calculation happens entirely on your device.
Worked example
A 6.1-inch phone at 2532 × 1170 has diagonal 2,789.25 px, so PPI = 457.25 ÷ ... ≈ 457.25 PPI.
FAQ
How is PPI calculated?
It takes the square root of the squared horizontal and vertical pixel counts to get the diagonal in pixels, then divides by the diagonal in inches.
What is dot pitch?
Dot pitch is the distance between pixels, here reported in millimetres, and a smaller value means a finer display.
Should resolution be whole pixels?
Yes. Pixel counts must be whole numbers, so the tool rejects fractional resolutions.
Does a bigger screen always mean lower PPI?
At the same resolution, yes; spreading the same pixels over a larger diagonal lowers the pixels per inch.