Display Density Tool
Screen PPI & DPI Calculator
Calculate the exact physical pixel density (Pixels Per Inch), dot pitch, and resolution metrics of any computer monitor, laptop, tablet, or smartphone.
Display PPI & DPI Calculator
Calculates raw physical panel pixel density and translates it to browser CSS coordinate space.
Hardware Pixels vs. Browser CSS Pixels:
Monitors have physical hardware pixels, but web browsers execute layout in CSS pixels. On high-density screens (Retina, 4K, smartphones), your operating system scales the display by a factor called devicePixelRatio (current browser DPR: —).
Common panel references:
Hardware Panel Density
91.8 hardware PPI
Estimated Browser CSS PPI (— DPR)
—
—
Physical Dot Pitch
276.7 µm
* Golden Rule of Accuracy: Hardware resolution calculations are theoretical estimates. Because operating systems apply custom fractional scaling (125%, 150%, 175%) that cannot be probed by JavaScript APIs, physical card calibration (85.60 mm) remains the only scientifically exact method to achieve true 1:1 real-world size.
Common Display Density Benchmarks (PPI Reference)
| Device / Panel Category | Typical Resolution | Diagonal | PPI (Pixels/Inch) |
|---|---|---|---|
| Generic 24" 1080p Desktop Monitor (1x scale) | Standard 1080p-4K | 24" | 91.8 PPI |
| Generic 27" 1440p (QHD) Desktop Monitor (1x scale) | Standard 1080p-4K | 27" | 108.8 PPI |
| Generic 27" 4K Desktop Monitor (150% OS scale) | Standard 1080p-4K | 27" | 163.2 PPI |
| Standard 15.6" 1080p Laptop (125% OS scale) | Standard 1080p-4K | 15.6" | 141.2 PPI |
| Standard 14" 1080p Laptop (125% OS scale) | Standard 1080p-4K | 14" | 157.4 PPI |
| MacBook Air 13.6" (Retina 2x scale) | Retina / High-DPI | 13.6" | 224 PPI |
| MacBook Pro 14" (Retina 2x scale) | Retina / High-DPI | 14" | 254 PPI |
| iPad Pro 11" (Liquid Retina 2x scale) | Retina / High-DPI | 11" | 264 PPI |
| iPhone 15 / 16 (Super Retina 3x scale) | Retina / High-DPI | 15" | 460 PPI |
Once you have your screen's PPI, you can apply it directly to the Online Ruler or verify it with our Card Calibration Wizard.