What this tool calculates
PPI (pixels per inch) measures pixel density. Using your diagonal and simplified aspect ratio, the calculator returns physical width × height (in or cm) and area, plus the aspect ratio reduced with GCD.
Popular resolutions & ratios
| Name | Pixels | Aspect |
|---|---|---|
| FHD | 1920×1080 | 16:9 |
| QHD | 2560×1440 | 16:9 |
| 4K UHD | 3840×2160 | 16:9 |
| UW 1440p | 3440×1440 | 21:9 |
| 5K2K | 5120×2160 | 21:9 |
| 8K UHD | 7680×4320 | 16:9 |
Pro tips
- For prints, target 300–350 DPI at final size; 200 DPI can work for large, far-viewed graphics.
- Keep the aspect ratio consistent from design to export (avoid letterboxing/cropping).
- Higher resolutions (4K/8K) allow sitting closer without visible pixels.
Formulas
PPI = √(W² + H²) ÷ Diagonal (in)
Width(in) = Diagonal × (AspectW ÷ √(AspectW² + AspectH²))
Height(in) = Diagonal × (AspectH ÷ √(AspectW² + AspectH²))
FAQs
What’s the difference between PPI and DPI?
PPI is pixel density on screens; DPI is print resolution. Use PPI for display sharpness, DPI for printing.
Why does my area change when I switch units?
Because inches ↔ centimeters convert by 2.54×; the area scales by 2.54².
Can I use decimals?
Yes—diagonal accepts decimals (e.g., 27.5″). Results are rounded for readability.