PPI Calculator
Calculate pixels per inch (PPI) for any display. PPI measures the pixel density of a screen — how many pixels are packed into each inch of display. Higher PPI means sharper text and images. Enter your screen resolution and diagonal size to find the PPI, dot pitch, and total pixel count. Also see our Pixels to Inches and Image Resolution Converter.
How to Calculate PPI
Formula:
PPI = √(width² + height²) ÷ diagonal (inches)
Dot Pitch (mm) = 25.4 ÷ PPI
First calculate the diagonal resolution in pixels using the Pythagorean theorem, then divide by the physical diagonal size in inches. The dot pitch is the physical distance between pixel centers, calculated by dividing 25.4 mm (1 inch) by the PPI.
PPI Reference Table
| Device | Resolution | Size | PPI |
|---|---|---|---|
| iPhone 15 Pro | 2556×1179 | 6.1" | 460 |
| MacBook Pro 14" | 3024×1964 | 14.2" | 254 |
| iMac 24" | 4480×2520 | 23.5" | 218 |
| 4K Monitor 27" | 3840×2160 | 27" | 163 |
| 1080p Monitor 24" | 1920×1080 | 24" | 92 |
| 1440p Monitor 27" | 2560×1440 | 27" | 109 |
| 4K TV 55" | 3840×2160 | 55" | 80 |
| iPad Pro 12.9" | 2732×2048 | 12.9" | 264 |
What is a Good PPI?
- 300+ PPI: Print quality — individual pixels invisible at any distance (smartphones, Retina displays)
- 200-300 PPI: Excellent — sharp at arm's length (tablets, laptop Retina screens)
- 100-200 PPI: Good — standard desktop monitors at normal viewing distance
- 70-100 PPI: Acceptable — large TVs viewed from couch distance
- Below 70 PPI: Low — pixels visible, suitable only for large displays viewed from far away
Frequently Asked Questions
What is the difference between PPI and DPI?
PPI (pixels per inch) refers to screen displays — how many pixels per inch on a monitor. DPI (dots per inch) refers to printing — how many ink dots per inch a printer produces. They are often used interchangeably but technically measure different things.
What PPI is Retina display?
Apple defines "Retina" as a display where individual pixels cannot be distinguished at a typical viewing distance. For iPhones this is 326+ PPI, for iPads 264 PPI, and for MacBooks 218-254 PPI (because they are viewed from farther away).
Does higher PPI mean better quality?
Yes, up to a point. Higher PPI means sharper text and images. However, beyond what your eyes can distinguish at your viewing distance, additional PPI provides no visible benefit. For a 27" desktop monitor at arm's length, 110+ PPI looks sharp to most people.
What is dot pitch?
Dot pitch is the physical distance (in mm) between the centers of adjacent pixels. Lower dot pitch = higher pixel density = sharper image. A 0.25mm dot pitch equals about 100 PPI.