PPI calculator
PPI — pixels per inch — is how tightly a screen packs its pixels. Give this calculator a resolution and a diagonal and it returns the density and the dot pitch, the physical size of one pixel.
The short answer
PPI = √(W² + H²) ÷ diagonal in inches. A 27″ 4K screen (3840 × 2160) comes to 163.18 PPI, so each pixel is 0.156 mm across. The same 1920 × 1080 resolution in a 24″ monitor gives 91.79 PPI — which is why a 24″ 1080p monitor looks softer than a 27″ 4K one, and why “4K” on a 75″ TV (about 59 PPI) is a completely different experience from “4K” on a monitor.
Reference devices — published specifications
The table below lists devices whose diagonal, native resolution and PPI are all published by their manufacturers. Only models we could verify against the maker's own spec pages are included; regional variants and unannounced models are left out on purpose. The “check” column is this site's engine recomputing PPI from the resolution and diagonal — it should land within a unit of the published figure (makers round their diagonals, e.g. a “6.1-inch” panel is not exactly 6.100 inches).
| Device | Diagonal | Resolution | Published PPI | Check (computed) | Dot pitch |
|---|---|---|---|---|---|
| iPhone SE (3rd gen, 2022) | 4.7″ | 1334 × 750 | 326 | 325.61 | 0.078 mm |
| iPhone 13 mini | 5.4″ | 2340 × 1080 | 476 | 477.26 | 0.053 mm |
| iPhone 12 / 13 / 14 | 6.1″ | 2532 × 1170 | 460 | 457.25 | 0.056 mm |
| iPhone 15 / 16 | 6.1″ | 2556 × 1179 | 460 | 461.44 | 0.055 mm |
| iPhone 16 Pro | 6.3″ | 2622 × 1206 | 460 | 458.10 | 0.055 mm |
| iPhone 16 Pro Max | 6.9″ | 2868 × 1320 | 460 | 457.56 | 0.056 mm |
| Samsung Galaxy S23 | 6.1″ | 2340 × 1080 | 425 | 422.49 | 0.060 mm |
| Samsung Galaxy S24 | 6.2″ | 2340 × 1080 | 416 | 415.68 | 0.061 mm |
| Samsung Galaxy S24 Ultra | 6.8″ | 3120 × 1440 | 505 | 505.33 | 0.050 mm |
| Google Pixel 7 | 6.3″ | 2400 × 1080 | 416 | 417.75 | 0.061 mm |
| Google Pixel 8 | 6.2″ | 2400 × 1080 | 428 | 424.48 | 0.060 mm |
| Google Pixel 9 | 6.3″ | 2424 × 1080 | 422 | 421.22 | 0.060 mm |
| MacBook Air 13" (M2) | 13.6″ | 2560 × 1664 | 224 | 224.51 | 0.113 mm |
| MacBook Air 15" (M2/M3) | 15.3″ | 2880 × 1864 | 224 | 224.22 | 0.113 mm |
| MacBook Pro 14" (M3/M4) | 14.2″ | 3024 × 1964 | 254 | 253.93 | 0.100 mm |
| MacBook Pro 16" (M3/M4) | 16.2″ | 3456 × 2234 | 254 | 254.02 | 0.100 mm |
| iPad (10th gen) | 10.9″ | 2360 × 1640 | 264 | 263.66 | 0.096 mm |
| iPad Air 11" (M2) | 11″ | 2360 × 1640 | 264 | 261.26 | 0.097 mm |
| iPad Pro 11" (M4) | 11.1″ | 2752 × 2064 | 264 | 309.91 | 0.082 mm |
| iPad Pro 13" (M4) | 13″ | 2752 × 2064 | 264 | 264.62 | 0.096 mm |
Common monitor classes
Standalone monitors are sold by size class rather than by model-specific panels, so this table pairs each common size with its typical native resolution and computes the density from those two numbers.
| Size class | Typical resolution | PPI (computed) | Dot pitch | Note |
|---|---|---|---|---|
| 21.5″ | 1920 × 1080 | 102.46 | 0.248 mm | |
| 23.8″ | 1920 × 1080 | 92.56 | 0.274 mm | |
| 24″ | 1920 × 1080 | 91.79 | 0.277 mm | |
| 24″ | 1920 × 1200 | 94.34 | 0.269 mm | |
| 27″ | 1920 × 1080 | 81.59 | 0.311 mm | |
| 27″ | 2560 × 1440 | 108.79 | 0.233 mm | |
| 27″ | 3840 × 2160 | 163.18 | 0.156 mm | |
| 31.5″ | 2560 × 1440 | 93.24 | 0.272 mm | |
| 32″ | 3840 × 2160 | 137.68 | 0.184 mm | |
| 34″ | 3440 × 1440 | 109.68 | 0.232 mm | ultrawide 21:9 class |
| 38″ | 3840 × 1600 | 109.47 | 0.232 mm | ultrawide |
| 49″ | 5120 × 1440 | 108.54 | 0.234 mm | super-ultrawide 32:9 class |
How to read a PPI number
- Phones, 400–500 PPI: held 25–35 cm from your eyes, so pixels need to be tiny. Beyond roughly 460 PPI most people cannot distinguish individual pixels at normal distance.
- Laptops, 200–260 PPI: the “Retina-class” zone — text looks print-smooth at a typical 50–60 cm viewing distance.
- Desktop monitors, 90–165 PPI: 1080p at 24″ (about 92) shows visible pixel structure if you look closely; 4K at 27″ (about 163) generally does not at arm's length.
- TVs, 40–90 PPI: perfectly adequate from 2–3 metres. Judge a TV by size and viewing distance together — the TV size calculator pairs them up.
PPI is a density, not a quality score: colour accuracy, brightness, contrast and refresh rate are separate specifications, and a modest-PPI screen viewed from the right distance will look sharper than a high-PPI screen viewed from too close.
Frequently asked questions
Is PPI the same as DPI?
On screens, people use the terms interchangeably. Strictly, PPI counts display pixels per inch while DPI counts printer dots per inch; the formula used here is the display one, from pixel resolution and physical diagonal.
Why is the computed PPI slightly different from the box spec?
Manufacturers round the diagonal in marketing names (a “27-inch” panel might be 27.0 or 26.9x inches) and sometimes round the PPI itself. A difference of one or two is rounding; a large difference usually means the resolution entered is the scaled/output resolution rather than the panel's native one.
Does a higher PPI use more battery or GPU power?
Indirectly: driving more pixels costs power, but that is set by the resolution, not the density figure. Two screens at 2560 × 1440 draw similar rendering load whether they are 27″ or 32″ — the 32″ just spreads the same pixels thinner.
What dot pitch is “good”?
Dot pitch is PPI turned upside down (25.4 ÷ PPI). Below about 0.15 mm per pixel, individual pixels are hard to see at desk distance; around 0.27 mm (a 24″ 1080p monitor) they are noticeable on text edges if you lean in.