How to convert pixels to centimetres
- 1.
Enter the size
Choose a unit (px, mm, cm or inches) and type the width and height.
- 2.
Choose the DPI
Use 300 DPI for printing photos and documents, 150 DPI for prints viewed from a distance, and 72 or 96 for screens. You can also enter your own value.
- 3.
Read the result
The table shows the same size in pixels, millimetres, centimetres and inches.
Formula: how to convert pixels to centimetres
A pixel has no fixed size. How many centimetres it covers depends on the resolution in DPI, which means pixels per inch. One inch is 2.54 cm, so:
- cm = px ÷ DPI × 2.54
- mm = px ÷ DPI × 25.4
- px = cm ÷ 2.54 × DPI
Example: an image 2480 px wide measures 2480 ÷ 300 × 2.54 ≈ 21.0 cm at 300 DPI. The same image at 150 DPI measures about 42.0 cm, because each pixel is twice as large.
How many centimetres is one pixel?
| DPI | 1 cm is | 1 px is |
|---|---|---|
| 72 | 28.35 px | 0.0353 cm |
| 96 | 37.80 px | 0.0265 cm |
| 150 | 59.06 px | 0.0169 cm |
| 300 | 118.11 px | 0.0085 cm |
| 600 | 236.22 px | 0.0042 cm |
The 96 DPI value comes from CSS, where 1 inch is 96 pixels. The 72 DPI value comes from the typographic point, which is 1/72 of an inch, so it shows up often in graphics programs and PDF files.
Which DPI should you use?
- 72 and 96 DPI: screens and websites. On a screen only the number of pixels matters, and the DPI stored in the file does not change how the image looks.
- 150 DPI: large prints viewed from a distance, such as posters, and draft prints of documents.
- 300 DPI: the standard for photos, flyers and documents printed for close viewing.
- 600 DPI: scans and prints with fine detail, such as line drawings.
The DPI stored in a file does not change the number of pixels. It only hints at the size at which a program should print the image. To change the pixel count, use the image resizer.
How many pixels is A4, A5, A3 and a 10×15 cm print?
A portrait A4 sheet (210×297 mm) is 2480×3508 px at 300 DPI and 1240×1754 px at 150 DPI. A 10×15 cm print is 1181×1772 px at 300 DPI. The full table for A3, A4, A5 and prints of 9×13, 10×15, 13×18, 15×21 and 20×30 cm is in the tool above.
The A3, A4 and A5 paper sizes follow the ISO 216 standard. Photo prints have nominal sizes, and labs may cut the paper a few millimetres off. For example, 10×15 cm often means 4×6 inches, which is 102×152 mm. The pixel counts for prints are therefore approximate. Check the exact size with the lab where you order the print.
For US Letter (8.5×11 in), choose inches as the unit and type 8.5 and 11: at 300 DPI that is 2550×3300 px.
Pixels are calculated with the formula in the first section and rounded to whole pixels. To set an image to such a size, use the image resizer, and if the photo proportions do not match the format, crop the image first.
A 35×45 mm photo in pixels
An ID photo of 35×45 mm is 413×531 px at 300 DPI and 827×1063 px at 600 DPI. The same conversion applies to other 35×45 mm photos, for example for student cards. The tool only converts dimensions. For framing, background and head size requirements, use the passport photo maker.
How large a print will my photo give?
Divide the photo pixels by 300 and multiply by 2.54 cm. A 4000×3000 px photo (12 megapixels) prints in good quality at up to 33.87×25.4 cm, about 13.3×10 inches. That is enough for A4 and for a 20×30 cm print. On A3 the pixels run short: the effective resolution is then about 241 DPI.
At 150 DPI the same photo gives a print of 67.73×50.8 cm, which can be enough for a poster viewed from a distance. Enlarging an image in a graphics program adds no detail. The program only interpolates the existing pixels, so the photo gets softer.
Frequently asked questions
How many centimetres is 1 pixel?
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How many pixels is an A4 sheet?
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How many pixels is a 10×15 cm photo?
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Does the DPI stored in a file change the number of pixels?
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What resolution do I need to print a photo?
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How do I convert cm to pixels?
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