DPI Calculator: Convert cm, mm & Inches to Pixels

DPI alone is not a size — you also need the print size. Pixels = inches × DPI. A print that is 20 cm wide at 300 DPI needs 20 ÷ 2.54 × 300 = 2362 pixels in width. Type the size and the DPI into the calculator above and it shows width and height in pixels.

A 50 × 70 cm poster needs 5906 × 8268 pixels at 300 DPI and 2953 × 4134 pixels at 150 DPI. A 70 × 100 cm poster needs 8268 × 11811 pixels at 300 DPI and 4134 × 5906 pixels at 150 DPI. Posters are seen from a distance, so 150 DPI is often enough.

Divide the length in centimeters by 2.54 to get inches, then multiply by the DPI. At 300 DPI, 10 cm is 10 ÷ 2.54 × 300 = 1181 pixels. The calculator above does this for width and height at once, and works in the other direction too.

At 300 DPI an A4 page (210 × 297 mm) is 2480 × 3508 pixels. At 150 DPI it is 1240 × 1754 pixels, and at 72 DPI it is 595 × 842 pixels.

PPI (pixels per inch) says how many image pixels are spread over one inch. DPI (dots per inch) strictly counts the ink dots a printer puts on paper — a printer uses many dots to build one pixel. In everyday use, and in the resolution label inside JPG and PNG files, “DPI” is used for pixels per inch as well. That is why this page says DPI in its name, but always means pixels per inch when it converts between pixels and centimeters.

No. DPI is only a label that says how large the picture should print. The number of pixels stays the same, so a 3000 × 2000 pixel photo is always 3000 × 2000 pixels. A higher DPI simply means a smaller print at the same sharpness. To really change the pixel size, use the Image Resizer.

For photos and documents held in your hand, 300 DPI is the usual target. Posters, banners and large prints are seen from further away, so 100–150 DPI is often enough. Use the “Check my image for printing” section above to see the DPI your photo reaches at each print size.

None — on screens only the pixel dimensions matter, not the DPI label. The 72 and 96 DPI values you may see are historical defaults. A 1200 pixel wide image looks the same on a website whether it is labelled 72 or 300 DPI.

A 35 × 45 mm passport photo, the common size in Europe, is 413 × 531 pixels at 300 DPI. Requirements differ by country, so check the exact size and background rules of the authority that will receive it. Use the Crop tool to cut the photo to the right proportions.

Yes. Add your image in “Check my image for printing”, choose the DPI and download a copy with that label. The picture itself is not resampled. For a JPG or PNG you can save the same file with only the label replaced — no re-encoding at all. Other files (WebP, HEIC, TIFF…) are saved again as JPG at 95% quality or as lossless PNG.

Yes. Each of the two panels has its own Undo and Redo buttons (or press Ctrl+Z and Ctrl+Shift+Z in the panel you are working in). They step back through the sizes, the DPI, the print size preset and the settings for saving a file.

No. The calculator and the image check run entirely in your browser. Your file never leaves your device.