By Ahsan Khowaja · Updated 27 October 2026
How to use the cm to pixel converter
- Keep photo or document size selected to enter a width and height, or choose single length for one measurement.
- Type the size and pick cm or mm next to each box. Photo requirements are often written in millimetres (35 × 45 mm) and paper sizes in centimetres (21 × 29.7 cm); both work.
- Set the resolution. Use the DPI the form, printer or scanner specifies. 300 DPI is the usual figure for photo prints and most upload portals, a few government portals ask for 200 DPI, and 96 PPI is what CSS uses when a web page says
1cm. - The result is the pixel size, rounded to whole pixels, with the exact unrounded value shown underneath, plus the total pixel count and the same size in inches. The table shows the pixels needed at every other resolution.
Then resize your image to those pixel dimensions. Our image resizer crops or fits to an exact pixel size in the browser; if the portal also sets a file-size limit, the KB reducer handles that step.
Centimeters to pixels formula
Pixels = cm ÷ 2.54 × PPI. Dividing by 2.54 turns centimetres into inches (an inch is exactly 2.54 cm), and multiplying by the pixels per inch gives the pixel count. For millimetres, divide by 25.4 instead. Because an image can only have whole pixels, the result is rounded.
- 1 cm in pixels: 1 ÷ 2.54 × 96 = 37.795, so 38 px on a 96 PPI screen; 118 px for a 300 DPI print.
- 6 × 3 cm in pixels at 300 DPI: 6 ÷ 2.54 × 300 = 708.66 and 3 ÷ 2.54 × 300 = 354.33, so 709 × 354 px.
- 200 cm to pixels: 200 ÷ 2.54 × 96 = 7,559 px at 96 PPI; for print it becomes 23,622 px, far more than most cameras capture along one side, which is why large banners are printed at 100 to 150 DPI.
A useful shortcut: print resolution of 300 DPI gives 118.11 pixels per centimetre, 96 PPI gives 37.795, and 72 PPI gives 28.346. Multiply the centimetres by that figure and round.
3.5 × 4.5 cm in pixels and other photo sizes at 300 DPI
Passport, visa and ID photos outside the US are usually specified in millimetres, and the application portal then wants a JPEG of a particular pixel size. The converter does the arithmetic; the official requirement itself comes from the issuing authority, so check its page for the exact size, head position and file limits before you upload.
| Photo size | Same size in mm | Pixels at 300 DPI | Pixels at 600 DPI |
|---|---|---|---|
| 2.5 × 3.5 cm | 25 × 35 mm | 295 × 413 px | 591 × 827 px |
| 3 × 4 cm | 30 × 40 mm | 354 × 472 px | 709 × 945 px |
| 3.5 × 4.5 cm | 35 × 45 mm | 413 × 531 px | 827 × 1,063 px |
| 3.5 × 5 cm | 35 × 50 mm | 413 × 591 px | 827 × 1,181 px |
| 4 × 6 cm | 40 × 60 mm | 472 × 709 px | 945 × 1,417 px |
| 5 × 5 cm | 50 × 50 mm | 591 × 591 px | 1,181 × 1,181 px |
| 5 × 7 cm | 50 × 70 mm | 591 × 827 px | 1,181 × 1,654 px |
| 6 × 3 cm | 60 × 30 mm | 709 × 354 px | 1,417 × 709 px |
A worked example from an Indian form: Protean's PAN card application lists the photo as 3.5 × 2.5 cm at 200 DPI, which is 3.5 ÷ 2.54 × 200 = 276 px by 2.5 ÷ 2.54 × 200 = 197 px, so 197 wide × 276 tall. Our PAN card photo size guide walks through that upload step by step, including the 20 KB file limit. Pick 200 DPI in the converter for forms like that.
A4 size in pixels and other paper sizes
Paper sizes are the other place centimetres meet pixels: scanning, designing a flyer, or exporting a page as an image. ISO paper sizes are defined in millimetres (A4 is 210 × 297 mm), so the pixel sizes below are rounded.
| Paper | Size in cm | 96 PPI (screen) | 150 DPI | 300 DPI (print) |
|---|---|---|---|---|
| A6 | 10.5 × 14.8 cm | 397 × 559 px | 620 × 874 px | 1,240 × 1,748 px |
| A5 | 14.8 × 21 cm | 559 × 794 px | 874 × 1,240 px | 1,748 × 2,480 px |
| A4 | 21 × 29.7 cm | 794 × 1,123 px | 1,240 × 1,754 px | 2,480 × 3,508 px |
| A3 | 29.7 × 42 cm | 1,123 × 1,587 px | 1,754 × 2,480 px | 3,508 × 4,961 px |
| A2 | 42 × 59.4 cm | 1,587 × 2,245 px | 2,480 × 3,508 px | 4,961 × 7,016 px |
| Business card | 8.5 × 5.5 cm | 321 × 208 px | 502 × 325 px | 1,004 × 650 px |
| 10 × 15 cm photo | 10 × 15 cm | 378 × 567 px | 591 × 886 px | 1,181 × 1,772 px |
| 13 × 18 cm photo | 13 × 18 cm | 491 × 680 px | 768 × 1,063 px | 1,535 × 2,126 px |
| 20 × 30 cm photo | 20 × 30 cm | 756 × 1,134 px | 1,181 × 1,772 px | 2,362 × 3,543 px |
A4 size in pixels at 300 DPI is 2,480 × 3,508 px, the figure most print templates use. Each A size has half the area of the one above, so two steps down halves both sides. That is why A2 at 150 DPI and A4 at the higher resolution both come to 2,480 × 3,508 px: halving the sides and doubling the resolution cancel out.
For a 10 × 15 cm photo print you need 1,181 × 1,772 px for full 300 DPI quality, about 2.1 megapixels. A 20 × 30 cm enlargement needs 2,362 × 3,543 px (8.4 MP). Any 12 MP phone photo (around 4032 × 3024 px) covers both; the print size calculator and dpi calculator tell you how far a given photo stretches.
Cm to pixels lookup table
Single lengths at the common resolutions, rounded to whole pixels:
| Length | 72 PPI | 96 PPI (CSS) | 150 DPI | 300 DPI |
|---|---|---|---|---|
| 1 mm | 3 px | 4 px | 6 px | 12 px |
| 5 mm | 14 px | 19 px | 30 px | 59 px |
| 1 cm | 28 px | 38 px | 59 px | 118 px |
| 2 cm | 57 px | 76 px | 118 px | 236 px |
| 2.54 cm (1 in) | 72 px | 96 px | 150 px | 300 px |
| 3 cm | 85 px | 113 px | 177 px | 354 px |
| 5 cm | 142 px | 189 px | 295 px | 591 px |
| 10 cm | 283 px | 378 px | 591 px | 1,181 px |
| 15 cm | 425 px | 567 px | 886 px | 1,772 px |
| 20 cm | 567 px | 756 px | 1,181 px | 2,362 px |
| 30 cm | 850 px | 1,134 px | 1,772 px | 3,543 px |
| 50 cm | 1,417 px | 1,890 px | 2,953 px | 5,906 px |
| 100 cm | 2,835 px | 3,780 px | 5,906 px | 11,811 px |
| 200 cm | 5,669 px | 7,559 px | 11,811 px | 23,622 px |
Mm to pixels: when the size is given in millimetres
Switch the unit next to the box to mm and type the millimetres directly; the converter divides by 25.4 before multiplying by the resolution. With 300 DPI, 35 mm is 413 px, 45 mm is 531 px, and 1 mm is 11.8 px (rounded to 12). At the CSS rate of 96 PPI, 1 mm is 3.78 px, which is also what a browser uses when a stylesheet says 1mm.
Cm to pixels on screen: the CSS case
Browsers follow the W3C's CSS Values and Units specification, which defines 1in as 96px and therefore 1cm as 37.795 px. A width: 5cm box is drawn 189 CSS pixels wide on every device, regardless of the screen's true density, so it only measures a real 5 cm on a 96 PPI monitor. If you want something to appear at a true size on a known screen, work out that screen's PPI with the PPI calculator or the screen size calculator and type it into the Custom box here.
