Convert Pixel per Inch (PPI) to Pixel per Millimeter
Live bidirectional calculator for Pixels per Inch (PPI) (PPI) and Pixels per Millimeter (pixel/mm) with verified formula and conversion charts.
Digital Image Resolution8 units
How the Calculation Works (Linear Scaling)
Since 1 Pixel per Millimeter = 25.4 Pixels per Inch (PPI), divide the value in Pixels per Inch (PPI) by 25.4.
Pixel per Inch (PPI) to Pixel per Millimeter Conversion Table
Precomputed values for quick reference and printing.
| Pixel per Inch (PPI) | Pixel per Millimeter |
|---|---|
| 1 PPI | 0.0394 pixel/mm |
| 2 PPI | 0.0787 pixel/mm |
| 3 PPI | 0.1181 pixel/mm |
| 4 PPI | 0.1575 pixel/mm |
| 5 PPI | 0.1969 pixel/mm |
| 6 PPI | 0.2362 pixel/mm |
| 7 PPI | 0.2756 pixel/mm |
| 8 PPI | 0.315 pixel/mm |
| 9 PPI | 0.3543 pixel/mm |
| 10 PPI | 0.3937 pixel/mm |
| 15 PPI | 0.5906 pixel/mm |
| 20 PPI | 0.7874 pixel/mm |
| 25 PPI | 0.9843 pixel/mm |
| 30 PPI | 1.1811 pixel/mm |
| 40 PPI | 1.5748 pixel/mm |
| 50 PPI | 1.9685 pixel/mm |
| 75 PPI | 2.9528 pixel/mm |
| 100 PPI | 3.937 pixel/mm |
| Pixel per Millimeter | Pixel per Inch (PPI) |
|---|---|
| 1 pixel/mm | 25.4 PPI |
| 2 pixel/mm | 50.8 PPI |
| 3 pixel/mm | 76.2 PPI |
| 4 pixel/mm | 101.6 PPI |
| 5 pixel/mm | 127 PPI |
| 6 pixel/mm | 152.4 PPI |
| 7 pixel/mm | 177.8 PPI |
| 8 pixel/mm | 203.2 PPI |
| 9 pixel/mm | 228.6 PPI |
| 10 pixel/mm | 254 PPI |
| 15 pixel/mm | 381 PPI |
| 20 pixel/mm | 508 PPI |
| 25 pixel/mm | 635 PPI |
| 30 pixel/mm | 762 PPI |
| 40 pixel/mm | 1016 PPI |
| 50 pixel/mm | 1270 PPI |
| 75 pixel/mm | 1905 PPI |
| 100 pixel/mm | 2540 PPI |
๐ Standard Benchmark Reference Values
Metric digital image resolution: exactly 25.4 pixels per inch.
Exact RatioAbout Pixel per Inch (PPI) (PPI)
A measure of digital display pixel density and bitmap image sampling resolution, expressing the number of addressable electronic pixels per linear inch (approx. 39.370 pixel/m). Distinct from DPI: PPI represents discrete digital color samples rather than analog ink droplets.
History: Adopted across computer monitor and digital photography standards (e.g. standard 72 PPI Mac, 96 PPI Windows, and modern 300โ460 PPI Retina/OLED mobile screens).
Common Uses: Smartphone and laptop display sharpness benchmarks, digital image file metadata (EXIF resolution tags), Photoshop canvas sizing.
About Pixel per Millimeter (pixel/mm)
A metric unit of digital image sampling resolution equal to 1,000 pixels per meter (approx. 25.4 PPI).
History: Used in medical imaging, flatbed document scanners, and micro-densitometers.
Common Uses: Medical radiology PACS scan resolution, flatbed scanner optical sensor benchmarks (e.g. 2400 scanner pixels/mm).
โ Frequently Asked Questions
How many Pixels per Millimeter are in 1 Pixel per Inch (PPI)?
There are exactly 0.03937 Pixels per Millimeter in 1 Pixel per Inch (PPI) (1 PPI = 0.03937 pixel/mm).
What is the formula to convert Pixel per Inch (PPI) to Pixel per Millimeter?
The formula is: Pixel per Millimeter = Pixel per Inch (PPI) / 25.4. Since 1 Pixel per Millimeter = 25.4 Pixels per Inch (PPI), divide the value in Pixels per Inch (PPI) by 25.4.
How do I convert 1 PPI to pixel/mm manually?
To convert 1 PPI to pixel/mm: apply the formula Pixel per Millimeter = Pixel per Inch (PPI) / 25.4. Substituting gives: 1 / 25.4 = 0.0394 pixel/mm.