Calculate millimeters from image pixels at a specified PPI, reverse mm to pixels, or check image resolution against a chosen print target. A pixel has no fixed physical size; CSS pixels and printer dots are different concepts.
Pixel To mm Formula
The following formula is used to calculate the conversion from pixels to millimeters.
Variables:
- MM is the size in millimeters
- P is the size in pixels
- DPI in this formula means image pixels per inch (PPI), an informal usage. A printer’s dots per inch is a different device specification; use the image PPI or measured display pixel density for this conversion.
To calculate the size in millimeters, first divide the size in pixels by the resolution (per inch) to get the size in inches. Then, multiply by 25.4 (the number of millimeters in an inch) to convert inches to millimeters.
| Pixels (px) | Millimeters (mm) @ 72 DPI | Millimeters (mm) @ 96 DPI | Millimeters (mm) @ 150 DPI | Millimeters (mm) @ 300 DPI | Millimeters (mm) @ 600 DPI |
|---|---|---|---|---|---|
| 16 | 5.64 | 4.23 | 2.71 | 1.35 | 0.68 |
| 24 | 8.47 | 6.35 | 4.06 | 2.03 | 1.02 |
| 32 | 11.29 | 8.47 | 5.42 | 2.71 | 1.35 |
| 48 | 16.93 | 12.70 | 8.13 | 4.06 | 2.03 |
| 64 | 22.58 | 16.93 | 10.84 | 5.42 | 2.71 |
| 72 | 25.40 | 19.05 | 12.19 | 6.10 | 3.05 |
| 96 | 33.87 | 25.40 | 16.26 | 8.13 | 4.06 |
| 120 | 42.33 | 31.75 | 20.32 | 10.16 | 5.08 |
| 128 | 45.16 | 33.87 | 21.67 | 10.84 | 5.42 |
| 150 | 52.92 | 39.69 | 25.40 | 12.70 | 6.35 |
| 192 | 67.73 | 50.80 | 32.51 | 16.26 | 8.13 |
| 256 | 90.49 | 67.73 | 43.35 | 21.67 | 10.84 |
| 300 | 105.83 | 79.38 | 50.80 | 25.40 | 12.70 |
| 360 | 127.00 | 95.25 | 60.96 | 30.48 | 15.24 |
| 400 | 141.11 | 105.83 | 67.73 | 33.87 | 16.93 |
| 480 | 169.33 | 127.00 | 81.28 | 40.64 | 20.32 |
| 600 | 211.67 | 158.75 | 101.60 | 50.80 | 25.40 |
| 720 | 254.00 | 190.50 | 121.92 | 60.96 | 30.48 |
| 960 | 338.67 | 254.00 | 162.56 | 81.28 | 40.64 |
| 1200 | 423.33 | 317.50 | 203.20 | 101.60 | 50.80 |
| *Assumes square pixels. Formula: mm = px × 25.4 / DPI. Common DPIs shown: 72, 96, 150, 300, 600. Note: 1 dpcm = 2.54 dpi. | |||||
What Does “Pixel to mm” Mean?
Pixel to mm is a conversion used in digital imaging to translate pixel units into physical millimeters. This conversion is crucial in graphic design, printing, and other fields where the physical size of an image or object is important. The conversion rate is not fixed and depends on the resolution (pixels per inch, often written as PPI; sometimes informally labeled as DPI). Higher resolution values result in more pixels per millimeter, leading to a higher level of detail in the printed image.
How to Calculate Pixel To mm?
The following steps outline how to calculate the Pixel To mm using the formula: MM = P / (DPI / 25.4).
- First, determine the size in pixels (P).
- Next, determine the resolution of the digital image (DPI).
- Next, calculate the value of DPI divided by 25.4.
- Finally, divide the size in pixels (P) by the value obtained in the previous step to calculate the size in millimeters (MM).
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem:
Use the following variables as an example problem to test your knowledge.
Size in pixels (P) = 800
Resolution of the digital image (PPI) = 300. The corresponding length is 800 × 25.4 / 300 ≈ 67.733 mm.
