Centimetres to Pixels at Any DPI
Type a print size in centimetres and get the pixels it needs at 300 DPI, or type pixels and get the centimetres back.
Local browser processing · No upload · No account required
Changing the tag keeps the picture data of a JPEG or PNG unchanged. It does not add pixels.
How to convert cm to pixels
The page starts at 300 DPI with a 10 × 15 cm print, the size of a standard photo print.
- Keep the print unit on cm. Type the print width or height in centimetres; the pixel field beside it fills in.
- Change the DPI if your lab gives one. The pixels follow at once, and the print fields show what the new pixels give.
- To go the other way, type pixels in the pixel fields. The print field shows the centimetres they make at the DPI you set.
- Press a paper button, such as A4, to set the pixels for a whole sheet at the current DPI.
Why I start at 10 × 15 cm
I start the page at 10 × 15 cm because it is the print most people order first. At 300 DPI it needs 1181 × 1772 px. A 12-megapixel frame of 4032 × 3024 px is far larger than that, and at 300 DPI it prints at 34.14 × 25.60 cm, so most phone photos give a 10 × 15 cm print with pixels to spare.
The cm field is the one to trust. I wrote the conversion to divide by 2.54 first, because a centimetre is that fraction of an inch, and then to multiply by the DPI. Every number on this page comes from that one line of arithmetic.
Common sizes in centimetres
| Print size (cm) | Pixels at 300 DPI | Pixels at 150 DPI |
|---|---|---|
| 10 × 15 | 1181 × 1772 | 591 × 886 |
| 13 × 18 | 1535 × 2126 | 768 × 1063 |
| 15 × 20 | 1772 × 2362 | 886 × 1181 |
| 20 × 25 | 2362 × 2953 | 1181 × 1476 |
| 20 × 30 | 2362 × 3543 | 1181 × 1772 |
| A4, 21 × 29.7 | 2480 × 3508 | 1240 × 1754 |
| A3, 29.7 × 42 | 3508 × 4961 | 1754 × 2480 |
| 50 × 70 | 5906 × 8268 | 2953 × 4134 |
Each pixel count is the centimetres divided by 2.54, times the DPI, rounded to a whole pixel. It is the same formula the calculator runs in your browser.
The formula, and why 10 cm is not exactly 1181 px
Pixels equal centimetres divided by 2.54, times the DPI. Ten centimetres is 3.937 inches, and 3.937 times 300 is 1181.1 pixels. The page rounds to 1181, because a picture has whole pixels only.
Going back, 1181 pixels at 300 DPI is 9.9991 cm. That reads as 10.00 cm to two decimals. The gap of under a tenth of a millimetre is the rounding to a whole pixel, not an error in the formula.
Choosing the DPI
The DPI is the only setting that changes the pixel count for a given size. Halve the DPI and the pixels halve, so 10 × 15 cm needs 591 × 886 px at 150 DPI, against 1181 × 1772 px at 300 DPI. The printed size of a fixed file moves the other way: 1181 px printed at 150 DPI is 20.00 cm wide.
Use the DPI your lab names. If it names none, 300 DPI is the figure this page starts from, and the rows above show what a lower value asks for.
Checks before you type a size
- Set the unit and the DPI before you type the size. Changing the unit recalculates the print fields from the pixels.
- Check the pixel count of your file against the pixels above. A cropped photo has fewer pixels, and so a smaller print.
- Keep the pixel count of the file you send. A 10 × 15 cm print needs 1181 × 1772 px at 300 DPI, and a smaller file prints smaller.
- Read the 150 DPI row as the largest sensible print for the same pixels, not as extra detail.
Privacy
Your photo never leaves your device. The page reads its size and DPI in your browser, and a changed photo is saved straight from this page.
Frequently asked questions
How many pixels is 10 cm at 300 DPI?
It is 1181 pixels. Ten centimetres is 3.937 inches, and 3.937 times 300 is 1181.1, rounded to 1181. The same 1181 pixels at 150 DPI would print 20.00 cm wide instead, so check the DPI before you crop.
How do I convert pixels back to centimetres?
Type the pixels in the pixel field. The print field shows the pixels divided by the DPI, times 2.54. For 1181 pixels at 300 DPI the result is 10.00 cm to two decimals.
Why are the pixel counts whole numbers?
An image has whole pixels only, so the page rounds to the nearest one. At 300 DPI one pixel is 0.0085 cm wide, so the rounding moves a print size by less than that. The print field shows the exact size the rounded count gives.
What is the difference between a centimetre and a pixel?
A centimetre is a length on paper, and a pixel is one dot in the file. The DPI links them: at 300 DPI each inch of paper takes 300 pixels, and each centimetre takes about 118.
Does the conversion depend on the photo I choose?
No. The conversion uses only the DPI and the size you type. A photo is needed only on the separate change DPI page, where the tag of a file is written. Here no file is opened or sent anywhere.
Related tools and guides
- Work out how large your photo can print: Convert pixels and print dimensions; change JPEG DPI tags.
- Inches to Pixels at 300 DPI: Type a print size in inches and get the pixels it needs at 300 DPI or any other DPI. The file pixels are not the same as CSS pixels.
- Change the DPI of an Image: Set the DPI tag of a JPEG or PNG to 300 in your browser. The pixels stay the same, and the page shows the print size before and after.
- Make a passport photo at home: Passport and visa photos to official sizes, with a printable 10 x 15 cm sheet.
- Make a contact sheet of your photos: Print a page of thumbnails with captions and EXIF lines as a PDF or page images.
- Print a Poster on Multiple Pages: Split a large image into paper sheets for a poster, with overlap and a printable PDF.
- I Built the Tools I Kept Looking For as a Photographer: Why these calculators run in the browser and never upload a file.
- Metelkova Ljubljana: My Photos and Complete Visitor Guide: Where the Metelkova photos on this site were taken.