Reference database
Screen PPI by Device
A reference of pixels-per-inch values for popular phones, tablets, laptops, and monitors. Use this to understand why online rulers need calibration and what screen density your device has.
PPI formula: sqrt(width² + height²) / diagonal inches. Values are rounded to the nearest whole number.
Phones
| Device | Resolution | Diagonal | PPI |
|---|---|---|---|
| iPhone 16 Pro Max | 2868x1320 | 6.9" | 460 |
| iPhone 16 Pro | 2622x1206 | 6.3" | 460 |
| iPhone 16 | 2556x1179 | 6.1" | 460 |
| iPhone 15 Pro Max | 2796x1290 | 6.7" | 460 |
| iPhone 15 Pro | 2556x1179 | 6.1" | 460 |
| iPhone 15 | 2556x1179 | 6.1" | 460 |
| iPhone 14 | 2532x1170 | 6.1" | 460 |
| iPhone SE (3rd gen) | 1334x750 | 4.7" | 326 |
| Samsung Galaxy S24 Ultra | 3120x1440 | 6.8" | 505 |
| Samsung Galaxy S24 | 2340x1080 | 6.2" | 416 |
| Samsung Galaxy A55 | 2340x1080 | 6.6" | 390 |
| Google Pixel 9 Pro | 2856x1280 | 6.3" | 495 |
| Google Pixel 9 | 2424x1080 | 6.3" | 422 |
| Google Pixel 8a | 2400x1080 | 6.1" | 431 |
| OnePlus 12 | 3168x1440 | 6.82" | 510 |
Tablets
| Device | Resolution | Diagonal | PPI |
|---|---|---|---|
| iPad Pro 13" (M4) | 2752x2064 | 13" | 264 |
| iPad Pro 11" (M4) | 2420x1668 | 11" | 264 |
| iPad Air 13" (M3) | 2732x2048 | 13" | 264 |
| iPad Air 11" (M3) | 2360x1640 | 11" | 264 |
| iPad (10th gen) | 2360x1640 | 10.9" | 264 |
| iPad mini (7th gen) | 2266x1488 | 8.3" | 326 |
| Samsung Galaxy Tab S9 Ultra | 2960x1848 | 14.6" | 240 |
| Samsung Galaxy Tab S9 | 2560x1600 | 11" | 274 |
Laptops
| Device | Resolution | Diagonal | PPI |
|---|---|---|---|
| MacBook Pro 16" (M3 Pro/Max) | 3456x2234 | 16.2" | 254 |
| MacBook Pro 14" (M3 Pro/Max) | 3024x1964 | 14.2" | 254 |
| MacBook Air 15" (M3) | 2880x1864 | 15.3" | 224 |
| MacBook Air 13" (M3) | 2560x1664 | 13.6" | 224 |
| Dell XPS 13 (2024) | 2560x1600 | 13.4" | 226 |
| Dell XPS 15 (2024) | 3456x2160 | 15.6" | 254 |
| ThinkPad X1 Carbon Gen 12 | 2880x1800 | 14" | 242 |
| Surface Laptop 7 | 2496x1664 | 13.8" | 215 |
| HP Spectre x360 14 | 2880x1800 | 14" | 242 |
| ASUS ZenBook 14 | 2560x1600 | 14" | 215 |
Monitors
| Device | Resolution | Diagonal | PPI |
|---|---|---|---|
| Apple Studio Display 27" | 5120x2880 | 27" | 218 |
| Apple Pro Display XDR 32" | 6016x3384 | 32" | 218 |
| Dell U2723QE 27" 4K | 3840x2160 | 27" | 163 |
| Dell U3423WE 34" WQHD | 3440x1440 | 34" | 110 |
| LG 27UK850-W 27" 4K | 3840x2160 | 27" | 163 |
| LG UltraFine 5K 27" | 5120x2880 | 27" | 218 |
| Samsung Odyssey G7 32" | 2560x1440 | 32" | 93 |
| ASUS ProArt PA279CV 27" 4K | 3840x2160 | 27" | 163 |
| BenQ PD2725U 27" 4K | 3840x2160 | 27" | 163 |
| Generic 24" FHD | 1920x1080 | 24" | 92 |
| Generic 27" QHD | 2560x1440 | 27" | 109 |
| Generic 32" 4K | 3840x2160 | 32" | 138 |
Why PPI matters for online rulers
The 96 PPI assumption
Browsers default to 96 CSS pixels per inch. On a 163 PPI monitor, an uncalibrated ruler would show objects at about 59% of actual size. On a 460 PPI phone, the error is even larger.
Calibration bridges the gap
By calibrating with a credit card, screen diagonal, or device auto-detection, the ruler learns the true pixels-per-millimeter ratio and draws tick marks at actual physical size.
Higher PPI = sharper but smaller default
High-PPI screens (Retina, QHD+) display more pixels per physical inch. Without calibration, a 1-inch ruler segment would measure much less than 1 inch physically.
Use this database to verify
If you know your device PPI from this table and our PPI calculator reports a similar value, your calibration is consistent. Use credit card calibration for the highest physical accuracy.
Frequently asked questions
What is screen PPI?+
PPI (pixels per inch) is the number of pixels packed into one physical inch of screen. Higher PPI means sharper text and graphics. It also determines how an online ruler must scale CSS pixels to draw actual-size tick marks.
How is PPI calculated?+
PPI = diagonal resolution in pixels / screen diagonal in inches. Diagonal resolution = sqrt(width^2 + height^2). For example, a 2560x1440 display at 27 inches has a diagonal pixel count of about 2943 and a PPI of about 109.
Why does PPI matter for online rulers?+
Browsers assume 96 CSS pixels per inch by default, but most modern screens have higher physical PPI. Without calibration, a ruler drawn at 96 PPI will appear smaller than actual size on a 163 PPI monitor. Calibration corrects this mismatch.
How do I find my screen's PPI?+
Look up your device in the database above, use the formula (diagonal pixels / diagonal inches), or use our PPI calculator tool. You can also calibrate with a credit card for practical accuracy without knowing your exact PPI.
Does OS display scaling affect PPI?+
Display scaling changes the effective CSS pixel density the browser sees, but not the physical PPI of your screen. Online rulers should be calibrated with scaling at the setting you normally use, and browser zoom at 100%.
Related tools
Screen PPI calculator
Calculate your screen's exact PPI from resolution and diagonal size.
Calibration guide
Learn how to calibrate the ruler using a credit card, screen diagonal, or auto-detection.
Online ruler
Measure actual size in cm, mm, and inches after calibration.