Pixels to MM Converter
This free pixels to mm converter turns pixels into millimeters (and millimeters back into pixels) instantly, using the web standard of 96 DPI by default. Because a pixel has no fixed physical size, you can switch the DPI to match your destination — 96 for screens, 300 for print. The conversion is bidirectional, so type a value in either field to see the other update. Everything runs entirely in your browser: nothing is uploaded, and there is no signup, so your measurements stay private.
How to use the pixels to mm converter
- Enter your measurement in the Pixels field.
- Choose a DPI (dots per inch) that matches where the value comes from — 96 for screens and web, 300 for print.
- Read the millimeter value, which updates instantly as you type.
- To go the other way, type into the Millimeters field and read the pixels — the tool is fully bidirectional.
- Copy the result into your design software, CSS, or print layout.
Every calculation happens locally in your browser, so nothing you enter is uploaded, stored, or shared.
The pixels to mm formula
Pixels are a resolution-dependent unit, so converting them to millimeters always involves a DPI value. The formula is:
mm = pixels × 25.4 ÷ DPI
This works because 1 inch = 25.4 mm, and DPI (dots per inch) tells you how many pixels fit into one inch. Multiplying pixels by 25.4 and dividing by DPI converts the pixel count into an inch measurement and then into millimeters.
Worked examples at the web default of 96 DPI:
- 1 px × 25.4 ÷ 96 = 0.2646 mm
- 100 px × 25.4 ÷ 96 = 26.46 mm
- 500 px × 25.4 ÷ 96 = 132.3 mm
To reverse the calculation, use pixels = mm × DPI ÷ 25.4. For example, 26.46 mm × 96 ÷ 25.4 = 100 px.
Why DPI (resolution) matters
There is no single fixed number of millimeters in a pixel — it depends entirely on the resolution you are working at. The same 100 px measures 26.46 mm on a standard screen but only 8.467 mm in a 300 DPI print file, because each context packs a different number of pixels into every inch.
- 96 DPI is the CSS and web default. Use it for websites, on-screen graphics, UI mockups, and social media. At 96 DPI, 1 px = 0.2646 mm.
- 72 DPI is a legacy screen value (1 px ≈ 0.3528 mm) still seen in some older design workflows.
- 150 DPI (1 px ≈ 0.1693 mm) is a middle ground for draft or low-cost printing.
- 300 DPI is the standard for high-quality print — brochures, posters, and photos. At 300 DPI, 1 px = 0.08467 mm.
The rule of thumb: match your DPI to the source of the pixels. A 1000 px image is a modest 84.67 mm wide at print resolution but a large 264.6 mm at web resolution, so getting the DPI right is what makes the millimeter figure meaningful.
Pixels to mm conversion table
| Pixels | MM @96 DPI | MM @300 DPI |
|---|---|---|
| 1 px | 0.2646 mm | 0.08467 mm |
| 10 px | 2.646 mm | 0.8467 mm |
| 50 px | 13.23 mm | 4.233 mm |
| 100 px | 26.46 mm | 8.467 mm |
| 300 px | 79.38 mm | 25.4 mm |
| 500 px | 132.3 mm | 42.33 mm |
| 1000 px | 264.6 mm | 84.67 mm |
Common export widths in millimeters
If you export images at a standard pixel width, it helps to know how wide that is on paper. These are typical widths converted at both web and print resolution:
| Pixel width | MM @96 DPI | MM @300 DPI |
|---|---|---|
| 800 px | 211.7 mm | 67.73 mm |
| 1080 px | 285.8 mm | 91.44 mm |
| 1200 px | 317.5 mm | 101.6 mm |
| 1920 px | 508 mm | 162.6 mm |
| 3543 px | 937.5 mm | 300 mm |
Notice that a full-HD 1920 px image is only about 162.6 mm wide at 300 DPI — roughly the width of A5 paper. To fill a 300 mm (A4-width) print sharply, you need 3543 px.
Preparing web images for print
Screen graphics are usually created at 96 DPI, so their pixel dimensions look generous but shrink dramatically once measured at print resolution. Before sending an image to a printer, decide the physical size you need in millimeters, then work backwards with pixels = mm × DPI ÷ 25.4 to check you have enough pixels. If a web image does not contain enough pixels for the target millimeter size at 300 DPI, enlarging it will look soft — it is better to re-export from the source at the higher resolution.
Frequently asked questions
How many mm is 1 pixel?
At 96 DPI (the web default), 1 pixel is 0.2646 mm. At 300 DPI for print, 1 pixel is 0.08467 mm. The exact figure is 25.4 ÷ DPI, so it changes with the resolution you pick.
How do I convert pixels to mm?
Multiply your pixel value by 25.4 and divide by the DPI: mm = pixels × 25.4 ÷ DPI. For example, 100 px at 96 DPI is 100 × 25.4 ÷ 96 = 26.46 mm. Or just type the value into the converter above and pick your DPI.
How many mm is 100 pixels?
At 96 DPI, 100 pixels is 26.46 mm. At 300 DPI it is 8.467 mm. Because pixels are resolution-dependent, the millimeter value depends on the DPI you choose.
Does a pixel have a fixed mm size?
No. A pixel is not a fixed physical length — its size in millimeters depends entirely on DPI. The same pixel is 0.2646 mm at 96 DPI but 0.08467 mm at 300 DPI, so you always need a resolution to convert.
What is the difference between px to mm and pixels to millimeters?
None — “px” is simply the abbreviation for pixels, and mm stands for millimeters. A px to mm conversion and a pixels to millimeters conversion give exactly the same result.
Which DPI should I use, 96 or 300?
Use 96 DPI when the pixels come from a screen, website, app, or social media, because that is the CSS default. Use 300 DPI when the pixels are from a print file so the physical size is accurate. Always match the DPI to where the image came from.
How do I convert mm back to pixels?
Reverse the formula: pixels = mm × DPI ÷ 25.4. For instance, 26.46 mm at 96 DPI is 26.46 × 96 ÷ 25.4 = 100 px. The converter does this automatically when you type in the millimeters field.
Is this pixels to mm converter free and private?
Yes. It is completely free, requires no signup, and runs entirely in your browser. Nothing you enter is uploaded to a server, so your measurements stay on your device.