What PPI means
Pixels per inch measures how tightly pixels are packed on a screen. The same resolution looks sharper on a smaller screen because the pixels are smaller and closer together. That's why a 24-inch 1080p monitor looks crisper than a 32-inch one at the same distance.
The formula
PPI = diagonal pixels ÷ diagonal inches
width (in) = diagonal × width ÷ diagonal pixels
blend distance (in) ≈ 3438 ÷ PPI
Example: 27-inch 1440p monitor
| Step | Result |
|---|---|
| Diagonal pixels: √(2560² + 1440²) | 2,937.2 |
| PPI: 2,937.2 ÷ 27 | 108.8 PPI |
| Size | 23.5 × 13.2 in |
| Pixels blend from | about 32 in |
Popular monitor sizes
| Size and resolution | PPI |
|---|---|
| 24-inch 1080p | 91.8 |
| 27-inch 1080p | 81.6 |
| 27-inch 1440p | 108.8 |
| 32-inch 1440p | 91.8 |
| 27-inch 4K | 163.2 |
| 32-inch 4K | 137.7 |
| 34-inch 3440 × 1440 ultrawide | 109.7 |
Frequently asked questions
How do you calculate PPI?
Find the diagonal resolution in pixels with Pythagoras, √(width² + height²), then divide by the diagonal size in inches. A 27-inch 2560 × 1440 monitor has a diagonal of about 2,937 pixels, so 2,937 ÷ 27 ≈ 109 PPI.
What is a good PPI for a monitor?
Around 90 to 110 PPI looks sharp at normal desk distance without scaling, which is why 24-inch 1080p and 27-inch 1440p are popular. 140 PPI and up (like 27-inch 4K at 163 PPI) looks very crisp but usually needs 125–150% scaling in Windows.
Is 1080p on a 27-inch monitor blurry?
It's about 82 PPI, so text looks softer and some people can see the pixel grid at typical desk distance. For 27 inches, 1440p is the common recommendation for sharpness.
What does the 'pixels blend' distance mean?
It's the distance beyond which a person with normal 20/20 vision can no longer pick out individual pixels, based on the eye resolving about 1 arcminute. Sitting closer than that, you may notice pixels or jagged edges; farther away, more resolution adds little.
Why is my phone's PPI so much higher?
Phones are held 10 to 12 inches from your eyes, so they need 400+ PPI to look as sharp as a monitor does at arm's length. The blend distance shown here explains the difference.
Rates and figures last checked October 2026.
This calculator gives estimates for planning. Check current rates and product labels before you buy, list or file.