PX to MM Converter
Result: 4.233mm
Calculation based on the CSS reference pixel of 3.7795275591 pixels per inch (96px = 25.4mm).
How to Use the Converter?
Select the input field labeled "Pixels"
Change the number in an input field
Converter will automatically convert
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PX to MM: How the Conversion Works
Pixels and millimeters serve very different purposes: pixels are digital units used in screens and CSS, while millimeters are a physical unit of length from the metric system. To convert between them, the calculation relies on the CSS standard of 96 pixels per inch, and since 1 inch equals 25.4mm, that works out to roughly 3.78px per millimeter.
This conversion is useful when adapting print measurements (common outside the US, where the metric system is standard) into digital design units, or when checking that a web-based design tool's dimensions will translate accurately to a printed, millimeter-measured document.
For example, an A4 page (210mm × 297mm) equals roughly 794px × 1123px at 96 DPI. A standard 85mm × 55mm business card (the common European size) equals about 321px × 208px.
Use the converter above to instantly switch between pixels and millimeters for any value.
Common PX to MM Conversions
10px
2.65mm
19px
5.03mm
38px
10.05mm
96px
25.4mm
189px
50mm
378px
100mm
567px
150mm
794px
210mm
Quick Conversion Tips
Converting PX to MM
Divide the pixel value by 3.7795275591. Example: 378px ÷ 3.78 ≈ 100mm
Converting MM to PX
Multiply the millimeter value by 3.7795275591. Example: 100mm × 3.78 ≈ 378px
Learn More About CSS Units
PX vs Inches, MM, and CM
Learn how pixels relate to inches, millimeters, and centimeters using the CSS 96 DPI standard, and avoid the most common print-design conversion mistake.
Read our comprehensive guide →Related Converters
Frequently Asked Questions
How many pixels are in a millimeter?
1 millimeter equals approximately 3.78px, based on the CSS standard of 96 pixels per inch (since 1in = 25.4mm).
How do I convert px to mm?
Divide the pixel value by 3.7795275591. For example, 96px ÷ 3.78 ≈ 25.4mm (1 inch). Use the converter above for instant results.
How do I convert mm to px?
Multiply the millimeter value by 3.7795275591. For example, 10mm × 3.78 ≈ 37.8px.
Why is the px to mm conversion not a whole number?
Because it derives from the 96 px-per-inch CSS standard combined with the metric definition of 25.4mm per inch, the ratio (about 3.78px per mm) isn't a round number.
Is this the same as print DPI?
No. Print devices often use higher resolutions such as 300 DPI. This conversion follows the CSS/web standard of 96 DPI, which is intended for screen and browser rendering.