Image Resolution Converter
Convert between DPI, PPI, dots per cm, and dots per mm for print and screen.
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How to use this calculator
- 1
Enter the resolution value you want to convert.
- 2
Select the unit you are converting from (e.g. DPI).
- 3
Select the target unit (e.g. dots per cm).
- 4
The result appears instantly.
Frequently asked questions
Which resolution units does the converter support?
Dots per inch (DPI), pixels per inch (PPI), dots per centimetre (dpcm) and dots per millimetre (dpmm). Inches are the base unit. DPI and PPI have the same value in the tool.
Are DPI and PPI the same?
Numerically, yes. They differ in meaning: PPI counts the pixels of a screen or digital image in each inch, while DPI counts the dots a printer places per inch. Printers often lay down several dots to render one pixel, so a printer’s DPI can be much higher than the PPI of the image it prints.
How do I convert DPI to dots per centimetre?
Divide by 2.54, since one inch is exactly 2.54 cm. Therefore 300 DPI is 118.1102362 dpcm and 150 DPI is 59.05511811 dpcm. Going the other way, multiply dpcm by 2.54.
What about dots per millimetre?
Divide DPI by 25.4. So 300 DPI is 11.81102362 dpmm, 600 DPI is 23.62204724 dpmm and 10 dpmm is 254 DPI. The metric forms appear in specifications written in centimetres or millimetres.
Does changing the DPI value make an image sharper?
No. DPI is metadata describing how large the pixels should print. The pixel count stays the same. Re-labelling a photo from 72 to 300 DPI changes the print size it suggests, not its detail.
Can this tool work out a print size or pixel dimensions?
No. It only converts one density unit to another. To find a print size, divide the image width in pixels by the PPI; to find the pixels needed, multiply the inches by the PPI. Do that separately.
Why are 72 and 96 often mentioned?
Those numbers are conventions rather than physical properties. Image editors have often assumed 72 PPI for screens, and CSS defines one inch as 96 CSS pixels. At 96 DPI the tool gives 37.79527559 dpcm, and at 72 DPI it gives 2.834645669 dpmm.
Resolution unit conversion: DPI, PPI, dpcm and dpmm
Density per inch, per centimetre, per millimetre
Image resolution says how many dots or pixels fit in a unit of length. Anglo-American workflows speak of inches, metric ones of centimetres or millimetres, and the numbers differ only because the length differs. With 2.54 cm per inch, one dpcm equals 2.54 DPI, and one dpmm equals 25.4 DPI.
| DPI or PPI | Dots per cm | Dots per mm |
|---|---|---|
| 72 | 28.34645669 | 2.834645669 |
| 96 | 37.79527559 | 3.779527559 |
| 150 | 59.05511811 | 5.905511811 |
| 300 | 118.1102362 | 11.81102362 |
| 600 | 236.2204724 | 23.62204724 |
Worked example: matching a metric print spec
A printer specification asks for 118.11 dpcm. The converter returns 299.9994 DPI, which is the familiar 300 within rounding. Likewise a screen listed at 326 PPI has 12.83464567 dots per mm, useful when comparing with a paper design measured in millimetres.
Worked example: from dots per mm back to inches
A scanner or engraver may quote 10 dpmm, which is exactly 254 DPI. A coarser 2.5 dpmm is 63.5 DPI, and 400 dpmm is 10,160 DPI. Converting through the same exact factor of 25.4 keeps these values clean.
What resolution does and does not change
Resolution is a ratio between pixels and physical size, so raising it without adding pixels shrinks the print. The converter does not resize images or resample them. For print work, pick the target size first, then the PPI you need, and only then compare it with the pixel dimensions your file actually has. A 600 DPI scan, for instance, packs 23.62204724 dots into each millimetre, which is a four-fold increase in pixel count over 300 DPI for the same sheet of paper.
Pixels, size and resolution together
Print size comes from three numbers: the pixel width, the resolution and the physical width. Fix any two and the third follows, so the usual task is to confirm the resolution in the unit your printer or software uses. Rounding is harmless for most jobs, but keep the exact value when a specification gives a tolerance. Convert the density here, then divide pixels by it. The tool shows the other three units at the same time, which helps when one program works in inches and another in centimetres. High numbers on spec sheets are not always better; viewing distance matters.
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