Screen PPI Calculator
Calculate the pixels per inch of any screen or display. Enter screen size and resolution, or choose from popular device presets. See if your display is Retina-class.
Screen Specifications
Display Metrics
PPI Rating Guide
What's PPI?
Pixels Per Inch - the density of pixels on a display. Formula: PPI = √(width² + height²) / diagonal_inches. So a 1920×1080 24-inch monitor: √(3686400+1166400) = √4852800 = 2202 / 24 = 91.78 PPI. Higher PPI = sharper image, more detail, smaller perceptible pixel size. iPhone displays: typically 460+ PPI (Retina). Standard desktop monitors: 90-110 PPI. 4K monitors at 27 inches: 163 PPI.
Why does PPI matter? Determines how large display elements appear at native resolution. A 24px font on 100 PPI = 0.24 inches tall. Same 24px on 200 PPI = 0.12 inches. Operating systems compensate via scaling (Windows display scaling, macOS Retina scaling) so apps remain readable across PPI ranges. Designers must consider PPI when designing for specific displays.
PPI by Common Devices
iPhone 15 Pro: 460 PPI (Retina). Samsung Galaxy S24: 416 PPI. iPad Pro: 264 PPI. MacBook Pro 14-inch: 254 PPI (Liquid Retina XDR). 27-inch 4K monitor: 163 PPI. 27-inch 1440p monitor: 109 PPI. 24-inch 1080p monitor: 92 PPI. Old-school 1024×768 17-inch CRT: 75 PPI. Modern phones average 4-5x desktop PPI density.
The 'Retina' threshold (where individual pixels become invisible at typical viewing distance) varies by device class. Phones held 30 cm from face: 300+ PPI is Retina. Tablets at 50 cm: 250+ PPI. Laptops at 60 cm: 200+ PPI. Desktop monitors at 80 cm: 110+ PPI. Beyond Retina threshold, more PPI is invisible to most users (some can detect up to 600+ PPI in high-detail scenes).
Why PPI Matters for Design
Design at native pixel dimensions for primary target. Rasterised graphics (logos, photos) look pixelated when scaled up - so design at the highest PPI you'll target. Modern best practice: design at 1x and 2x (Retina) or rely on responsive design with vector (SVG) graphics that scale infinitely. Don't design at 1080p only and hope it scales - it'll look blurry on 4K.
CSS handles PPI translation: 1 CSS pixel = ~96 PPI baseline. Browsers scale CSS pixels to actual device pixels (a CSS 24px font might use 48 actual device pixels on Retina displays). The 'device-pixel-ratio' lets developers detect and respond to high-DPI screens. Modern responsive design assumes Retina/high-DPI by default.
Calculating Your Screen's PPI
1) Note your screen's native resolution (e.g. 2560×1440). 2) Note diagonal screen size in inches (e.g. 27 inches). 3) Calculate diagonal pixels: √(width² + height²). 4) Divide by diagonal inches to get PPI. So 2560×1440 27-inch: √(6553600+2073600) = √8627200 = 2937 / 27 = 108.79 PPI.
Online PPI calculators (this tool) handle the math. Useful for: comparing monitors before buying, understanding why your design looks different on different screens, sizing design assets correctly for target devices, troubleshooting visual issues across devices. Use the [Image File Size Calculator](/image-file-size-calculator) for image sizing decisions; PPI affects required image dimensions.
Frequently Asked Questions
What's the highest PPI display?
Top consumer phones (iPhone 15 Pro, Samsung Galaxy S24): 460-500 PPI. VR headsets: 1000+ PPI for individual eye displays. Some specialised medical/research displays: 1500+ PPI. Diminishing returns past 500 PPI for typical viewing - the human eye can't distinguish more pixels at typical distance.
Does higher PPI hurt battery?
Yes - more pixels = more processing. High-PPI displays consume 20-40% more battery for graphics-heavy tasks. Most modern devices implement smart scaling: render at lower internal resolution then upscale for display, balancing visual quality with battery life.
Is 4K worth it on small screens?
Diminishing returns past Retina threshold. A 27-inch 4K monitor (163 PPI) shows visible improvement over 1440p (109 PPI). A 13-inch 4K laptop (340 PPI) hits Retina easily; visual improvement over 1440p (227 PPI) is minimal. Battery impact and software scaling issues sometimes outweigh visual gain.
What about DPI vs PPI?
Often used interchangeably but technically different. DPI = Dots Per Inch, used for printing (ink dots). PPI = Pixels Per Inch, used for digital displays. Same math but different physical concept. Image files stored with metadata DPI value (300 DPI for print, 72 PPI traditional web).
Related Tools
Pixel DPI Calculator
Calculate pixels, DPI, PPI and physical print sizes. Convert between pixels and mm, cm, or inches at any resolution. Essential for designers and photographers.
Megapixel Calculator
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Screen Size Calculator
Calculate the actual width and height of a screen from its diagonal size and aspect ratio. Useful when buying monitors, TVs, or tablets.
Aspect Ratio Calculator
Calculate and convert aspect ratios for images and video. Lock ratios, use platform presets for Instagram, YouTube, TikTok, and more. Shows megapixels and orientation.