PPI Calculator
Calculate pixels per inch (PPI/DPI) for any screen. Enter resolution and diagonal size to find pixel density, compare against common displays, and check retina display thresholds.
Common displays
Screen Pixel Density
Pixel Density
92
PPI
Low density
Resolution
1920 × 1080 px
Total pixels
2.07 MP
Pixel pitch
0.277 mm
Diagonal
24" (609.6 mm)
Width (physical)
20.92"
Height (physical)
11.77"
Retina thresholds
📱iPhone Retina (326+)
92/326
⬜iPad Retina (264+)
92/264
💻Mac Retina (226+)
92/226
Common Display PPI Comparison
| Display | Resolution | PPI |
|---|---|---|
| iPhone 16 | 2556×1179 @ 6.1" | 461 |
| iPhone SE (3rd gen) | 1334×750 @ 4.7" | 326 |
| iPad Pro 13" | 2752×2064 @ 13" | 265 |
| MacBook Pro 14" | 3024×1964 @ 14.2" | 254 |
| MacBook Air 13" | 2560×1664 @ 13.6" | 225 |
| LG 27" 4K | 3840×2160 @ 27" | 163 |
| Dell 27" 1440p | 2560×1440 @ 27" | 109 |
| FHD 24" Monitor | 1920×1080 @ 24" | 92 |
| Samsung 65" 4K TV | 3840×2160 @ 65" | 68 |
How to Use PPI Calculator
- 1Enter your screen resolution (width × height in pixels).
- 2Enter the diagonal screen size in inches.
- 3View the PPI, compare to common displays, and see if it qualifies as retina.
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Frequently Asked Questions
What is PPI (pixels per inch)?▾
PPI (pixels per inch) measures the pixel density of a screen — how many pixels fit in one inch in any direction. Formula: PPI = √(width² + height²) / diagonal_inches. Higher PPI means sharper, crisper images. The human eye can generally distinguish individual pixels below ~300 PPI at normal viewing distance (12-18 inches). Apple coined "Retina display" for screens where pixels cannot be distinguished at typical viewing distance — currently 226+ PPI for Macs, 326 PPI for iPhones. DPI (dots per inch) is technically for printing, but often used interchangeably with PPI for displays.
What is Apple's Retina display threshold?▾
Apple's Retina display threshold varies by device category: iPhone: 326 PPI (since iPhone 4). iPad: 264 PPI (since iPad 3rd gen). MacBook/iMac: 226 PPI (since 2012 Retina MacBook Pro). Apple Watch: 326-330 PPI. The threshold is based on viewing distance — iPhone is held closer (~12"), Mac is viewed from farther (~24"). Google's Pixel phones are typically 411-430 PPI. OLED display on Apple Vision Pro: ~3,400 PPI. 8K displays at 85" diagonal are ~104 PPI, but viewed from ~6-8 feet away.
What is the difference between 1080p, 4K, and 8K?▾
1080p (Full HD): 1920×1080 pixels = 2.07 megapixels. 4K (UHD): 3840×2160 = 8.29 megapixels — 4× the pixels of 1080p. True 4K (DCI): 4096×2160. 8K (FUHD): 7680×4320 = 33.18 megapixels — 16× 1080p. For a 27" monitor: 1080p ≈ 82 PPI, 1440p ≈ 109 PPI, 4K ≈ 163 PPI. HDMI 2.1 supports 8K at 60Hz. The benefit of higher resolution depends on viewing distance — at 10 feet, 1080p on a 65" TV is about the same as 4K at the same distance.
How does screen size affect perceived sharpness?▾
The same resolution on a smaller screen = higher PPI = sharper image. Example: 4K on a 27" monitor = ~163 PPI (very sharp). 4K on a 65" TV viewed at 6 feet = still sharp because viewing distance increases. Rule of thumb: perceived sharpness depends on angular resolution (pixels per degree of visual angle). Normal human vision resolves ~60 arc-minutes = 1 arc-degree. At 24" distance, comfortable limit is ~300 PPI. At 6 feet, ~75 PPI is sufficient. Retina thresholds: iPhone ~326+ PPI at 12", iPad ~264+ PPI at 15", Mac ~227+ PPI at 24".
What is subpixel rendering and how does it relate to PPI?▾
Subpixel rendering (ClearType on Windows, subpixel anti-aliasing) treats each RGB subpixel as a separate display element, effectively tripling horizontal resolution for text. At low PPI (<150), this significantly improves text readability. At high PPI (>250+), subpixel rendering offers less benefit and may even cause color fringing on OLED displays where subpixels are arranged differently. macOS disabled subpixel anti-aliasing in Mojave because Retina displays are sharp enough without it. OLED panels use stripe (Samsung), PenTile (diamond), or other arrangements that affect effective resolution.