Millimeters to Pixels Calculator
Enter a length in millimeters and a resolution value (DPI/PPI) to instantly convert mm to px.
How to convert mm to pixels
To convert millimeters to pixels, you need one critical value: resolution. Pixel values are not physical units by themselves, so the same millimeter length can map to different pixel counts depending on the DPI (dots per inch) or PPI (pixels per inch).
Why 25.4? Because there are exactly 25.4 millimeters in one inch. Once you convert mm to inches, you multiply by DPI to get pixels.
Quick examples
- 10 mm at 96 DPI = 37.80 px
- 25 mm at 96 DPI = 94.49 px
- 50 mm at 300 DPI = 590.55 px
- 210 mm (A4 width) at 300 DPI = 2480.31 px
Common mm to pixel reference table
| Millimeters | 72 DPI | 96 DPI | 150 DPI | 300 DPI |
|---|---|---|---|---|
| 10 mm | 28.35 px | 37.80 px | 59.06 px | 118.11 px |
| 25 mm | 70.87 px | 94.49 px | 147.64 px | 295.28 px |
| 50 mm | 141.73 px | 188.98 px | 295.28 px | 590.55 px |
| 100 mm | 283.46 px | 377.95 px | 590.55 px | 1181.10 px |
Choosing the right DPI for your project
For screens and web graphics
Most web and UI work is designed around pixel dimensions first, but if you are translating a physical size to screen design, 96 DPI is often used as a baseline reference. This is practical for mockups and rough planning.
For printing
Use 300 DPI for high-quality print output (posters, brochures, photo books, and professional documents). 150 DPI can be acceptable for large-format prints viewed from a distance. 72 DPI is generally too low for modern print standards.
Why mm to px matters
Accurate mm to pixel conversion helps prevent blurry artwork, unexpected scaling, and layout issues. Designers, students, photographers, and print professionals use this conversion when:
- Preparing print-ready images with exact physical dimensions
- Designing labels, business cards, and packaging
- Converting paper sizes like A4, A5, or custom measurements to pixel dimensions
- Creating technical drawings and digital templates
Frequently asked questions
Is DPI the same as PPI?
In many everyday workflows, people use the terms interchangeably. Technically, PPI refers to digital pixel density and DPI refers to print dot density, but for this calculator they function the same for conversion purposes.
Can I convert px back to mm?
Yes. Reverse formula: mm = (pixels × 25.4) ÷ DPI. You still need a DPI value to make that conversion meaningful.
Why are my results decimals instead of whole numbers?
Because millimeters often convert to fractional pixels. In practice, software may round to the nearest pixel. For precision workflows, keep decimals until your final export step.
Tip: If you are preparing files for print, confirm DPI and final trim size with your printer before exporting.