Formula and method
centimeters = pixels ÷ PPI × 2.54
PPI creates the bridge between a pixel count and a physical length. Without a PPI value there is no single correct pixels-to-centimeters conversion.
Assumptions and limits
- PPI is known or intentionally selected for the target medium.
- The same PPI applies horizontally and vertically.
- Rounding is for display only; calculations keep full precision.
Worked examples
300 pixels at 300 PPI
300 ÷ 300 = 1 inch. Multiplying by 2.54 gives exactly 2.54 cm.
10 cm at 96 PPI
10 ÷ 2.54 × 96 = about 377.95 pixels, usually rounded to 378 pixels for a bitmap.
300 pixels at common PPI values
| PPI | Inches | Centimeters | Typical context |
|---|---|---|---|
| 72 | 4.167 in | 10.583 cm | Legacy screen or design preset |
| 96 | 3.125 in | 7.938 cm | CSS pixel reference and web mockups |
| 150 | 2.000 in | 5.080 cm | Large posters and distance viewing |
| 300 | 1.000 in | 2.540 cm | Close-viewed photo printing |
Frequently asked questions
How many pixels are in one centimeter?
It depends on PPI. At 96 PPI there are about 37.8 pixels per centimeter; at 300 PPI there are about 118.1.
Why does a web image not have a fixed centimeter size?
Browsers and screens can display the same pixel image at different physical sizes depending on CSS, scaling and display density.
Which PPI should I choose?
Use the PPI required by the final medium: 96 for many web layouts, 150 for posters, and 300 for close-viewed print work.
Can I convert centimeters back to pixels?
Yes. Divide centimeters by 2.54 and multiply by PPI to get the required pixel count.