Screen Pixel Density (ppi)
Resolution alone does not tell you sharpness — 4K on a large panel still has large pixels. Diagonal pixels over diagonal inches gives ppi, the figure that matters, alongside the size of one pixel.
Your numbers
Pixel density (ppi)
108.8ppi
Diagonal
2,937px
Result
0.2335cm
What it means
108.8 ppi shows pixels up close; text edges look rough.
Formula
Pixel density (ppi) = √(Width in pixels ² + Height in pixels ²) ÷ Inches
Perceived sharpness also depends on viewing distance. A phone held close wants 300 ppi; a monitor at arm’s length often looks fine at 110.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Width in pixels (px)How many pixels across the screen. | 2,560 | 1 and up |
| Height in pixels (px)How many pixels down the screen. | 1,440 | 1 and up |
| InchesThe diagonal in inches — screens are always named by the diagonal. | 27 | 1 and up |
Step by step
Quick reference table
Results when only Width in pixels (px) changes and everything else stays put.
| Width in pixels (px) | Pixel density (ppi) (ppi) | Diagonal (px) | Result (cm) |
|---|---|---|---|
| 1,280 | 71.4 | 1,927 | 0.356 |
| 1,920 | 88.9 | 2,400 | 0.2858 |
| 2,560 | 108.8 | 2,937 | 0.2335 |
| 3,840 | 151.9 | 4,101 | 0.1672 |
| 5,120 | 197 | 5,319 | 0.1289 |
What each result means
| Result | At default values |
|---|---|
| Pixel density (ppi) (ppi)Pixels packed into one inch; higher is sharper. | 108.8 |
| Diagonal (px)Corner to opposite corner. | 2,937 |
| Result (cm)What the formula gives back — the answer this page is for. | 0.2335 |
Common mistakes
Perceived sharpness also depends on viewing distance. A phone held close wants 300 ppi; a monitor at arm’s length often looks fine at 110.
Glossary
- Width in pixels
- How many pixels across the screen.
- Height in pixels
- How many pixels down the screen.
- Inches
- The diagonal in inches — screens are always named by the diagonal.
- Pixel density (ppi)
- Pixels packed into one inch; higher is sharper.
- Diagonal
- Corner to opposite corner.
- Result
- What the formula gives back — the answer this page is for.
Frequently asked questions
Q. How is Screen Pixel Density (ppi) calculated?
Pixel density (ppi) = √(Width in pixels ² + Height in pixels ²) ÷ Inches — Resolution alone does not tell you sharpness — 4K on a large panel still has large pixels. Diagonal pixels over diagonal inches gives ppi, the figure that matters, alongside the size of one pixel.
Q. Can you walk through an example?
With Width in pixels 2,560px, Height in pixels 1,440px, Inches 27, the answer is Pixel density (ppi) 108.8ppi.
Q. What do I need to enter?
Enter Width in pixels, Height in pixels, Inches. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Width in pixels (px) moves the answer to Width in pixels (px) 1,280 → Pixel density (ppi) (ppi) 71.4 and Width in pixels (px) 5,120 → Pixel density (ppi) (ppi) 197. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Perceived sharpness also depends on viewing distance. A phone held close wants 300 ppi; a monitor at arm’s length often looks fine at 110.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.