PPI Calculator - Pixel density and screen comparison
Pixel density from resolution and size: PPI, pixel pitch and up to four screens compared.
Compare screens by true pixel density
- Type each screen resolution in pixels — for example 1920 by 1080 — and the physical diagonal in inches or centimeters. Comma decimals work.
- Worked example: 1920×1080 has a pixel diagonal of √(1920² + 1080²) ≈ 2202.91 px. On a 24 in screen that is 2202.91 ÷ 24 ≈ 91.79 PPI, with a pixel pitch of 25.4 ÷ 91.79 ≈ 0.2767 mm.
- Pick which screen is the base of the comparison. The table shows every other screen as a signed percent difference in PPI.
- Read the proportional drawing as relative sizes only: it scales the screens to each other and never claims real-size rendering.
- Need a size for a sharpness goal instead? Use the inverse mode: resolution plus target PPI gives the diagonal that reaches it.
- Copy the text summary, export the table as CSV, or copy a link that reopens the same screens.
Pixel density questions
Why do you need the diagonal, not just the resolution?
Resolution alone says nothing about sharpness: 1920×1080 on a 24 in monitor is about 91.79 PPI, but the same pixels on a 55 in TV are only about 40 PPI. Density is pixels divided by physical size, so both numbers are required.
What does the math assume?
Square pixels and a diagonal measured over the active area, bezels excluded. That covers virtually every modern LCD, OLED and phone panel; exotic subpixel layouts still share the same PPI definition.
Can the page detect my monitor size automatically?
No, and neither can any website: browsers expose the CSS pixel ratio (devicePixelRatio), which is a software zoom scale, not the physical inches of your panel. Measure the diagonal with a tape or read the manufacturer spec.
Is a higher PPI always the better buy?
Not universally. A 110 PPI desktop monitor at arm's length can look perfectly sharp, while a phone needs 400+ because it sits centimeters from your eyes. Viewing distance, scaling and use (code, games, photo, couch TV) matter more than the number alone.
How does the inverse mode work?
It turns the formula around: diagonal = pixel diagonal ÷ target PPI. For 1920×1080 at a 110 PPI goal, 2202.91 ÷ 110 ≈ a 20.03 in screen — useful when choosing a monitor size for a sharpness target.