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How many pixels are in a centimeter?
There is no single answer, because a pixel has no fixed size until you pick a resolution. A pixel to cm converter needs the DPI (dots per inch, also called PPI). At 300 DPI there are 118.11 pixels in one centimeter. At 96 DPI, the number browsers assume for screens, there are 37.8.
pixels = cm ÷ 2.54 × DPI
mm = cm × 10 | inch = cm ÷ 2.54 | pt = inch × 72
Worked example: a 1080 px wide Instagram post printed at 300 DPI is 1080 ÷ 300 × 2.54 = 9.14 cm wide. The same file at 96 DPI is 28.58 cm wide. The pixels did not change, only the size you spread them over.
Pixels per cm at common DPI
| DPI | Pixels per cm | Size of one pixel | Typical use |
|---|---|---|---|
| 72 | 28.35 | 0.353 mm | Old screen and PDF default |
| 96 | 37.80 | 0.265 mm | CSS and Windows screens |
| 150 | 59.06 | 0.169 mm | Draft prints, large posters |
| 300 | 118.11 | 0.085 mm | Photos, documents, ID photos |
| 600 | 236.22 | 0.042 mm | Line art, scans of small items |
How many pixels is an ID photo or A4 page?
These are the sizes at 300 DPI, rounded to whole pixels. For online forms that ask for a photo "3 × 4 cm", send 354 × 472 px.
| Size | At 300 DPI | At 150 DPI |
|---|---|---|
| 2 × 3 cm photo | 236 × 354 px | 118 × 177 px |
| 3 × 4 cm photo | 354 × 472 px | 177 × 236 px |
| 4 × 6 cm photo | 472 × 709 px | 236 × 354 px |
| 4 × 6 in print | 1200 × 1800 px | 600 × 900 px |
| 8 × 10 in print | 2400 × 3000 px | 1200 × 1500 px |
| A5 (14.8 × 21 cm) | 1748 × 2480 px | 874 × 1240 px |
| A4 (21 × 29.7 cm) | 2480 × 3508 px | 1240 × 1754 px |
| A3 (29.7 × 42 cm) | 3508 × 4961 px | 1754 × 2480 px |
At 72 DPI an A4 page is 595 × 842 px, and at 96 DPI it is 794 × 1123 px. Those are the numbers design apps use when you create an "A4" canvas for screen work.
What DPI do I need to print a photo?
Divide the photo's pixel width by the print width in inches. A 4000 × 3000 px phone photo printed at 30 cm wide (11.8 in) gives 339 DPI, which looks sharp. Stretched to a 60 cm poster it drops to 169 DPI, fine from a few steps away and soft up close. The helper at the bottom of the tool does this sum for you and also tells you how many pixels you would need for 300 DPI.
- 300 DPI or more: sharp at reading distance. Use it for photos, ID pictures and anything with small text.
- 200 to 299 DPI: good for most prints and hard to tell from 300 by eye.
- 150 to 199 DPI: acceptable for posters you look at from further away.
- Under 100 DPI: pixels become visible. Large banners are the exception, since people see them from several meters away.
These are rules of thumb, not standards. A printer with a good print shop behind it can often tell you the minimum they accept.
Does changing DPI change the image?
No. DPI stored inside a file is only a label that says how large to print it. A 3000 × 2000 px photo tagged 72 DPI and the same photo tagged 300 DPI hold identical pixels. Changing the tag does not add detail. To get a sharper print you need more pixels, meaning a bigger original, not a bigger number in the metadata. When you upload a photo above, the tool shows the DPI tag if the file has one, but works from the pixel size.
Pixels on a screen are not centimeters
A phone screen can have 400 physical pixels per inch while a CSS pixel is still defined as 1/96 inch. That is why 1 cm on your screen is never exactly 37.8 on-screen pixels. Use the DPI conversion for print, and for screen layouts think in pixels only.
Frequently asked questions
How do I convert pixels to cm?
Divide the pixels by the DPI and multiply by 2.54. For example, 1080 px at 300 DPI is 1080 ÷ 300 × 2.54 = 9.14 cm. At 96 DPI the same 1080 px is 28.58 cm.
How many pixels is 1 cm?
At 300 DPI, 1 cm is 118.11 pixels. At 96 DPI it is 37.8 pixels, and at 72 DPI it is 28.35 pixels. The number depends on the DPI, so pick the one your print or screen uses.
How many pixels is A4?
At 300 DPI, A4 (21 × 29.7 cm) is 2480 × 3508 pixels. At 150 DPI it is 1240 × 1754, at 96 DPI it is 794 × 1123 and at 72 DPI it is 595 × 842.
How many pixels is a 3x4 cm photo?
At 300 DPI a 3 × 4 cm photo is 354 × 472 pixels. A 2 × 3 cm photo is 236 × 354 and a 4 × 6 cm photo is 472 × 709, also at 300 DPI.
What DPI should I use for printing?
Use 300 DPI for photos and documents, 150 DPI for large posters seen from a distance, and even less for big banners. Enter your image size in the helper and it shows the DPI you would actually get.
Does DPI change the quality of an image?
No. DPI is only a print size label stored in the file. A 3000 × 2000 px image has the same pixels at 72 or 300 DPI. More quality needs more pixels, not a different DPI tag.
What is the difference between DPI and PPI?
PPI counts pixels per inch in an image or screen, while DPI counts printed dots per inch. For converting sizes the two are used the same way, so this tool treats them as one number.
How do I convert cm to pixels for a banner?
Enter the banner width and height in cm, set From to cm and To to px, then choose a DPI. A 60 × 160 cm X-banner needs 3543 × 9449 px at 150 DPI. Large banners are often printed at 100 DPI or less.