Digital Resolution Converter
Convert digital resolution between dots per inch (DPI), pixels per inch (PPI), dots per centimetre (DPCM), and dots per millimetre (DPMM).
How to use this tool
- Enter resolution and from unit in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your dpcm and the full breakdown beneath it.
Formula
All values convert to a base in DPI first, then divide by the target factor:
base (DPI) = input × factorfrom
Factors: 1 DPI = 1 PPI, 1 DPCM = 2.54 DPI, 1 DPMM = 25.4 DPI.
Since 1 inch = 2.54 cm = 25.4 mm, these factors follow directly from the length conversion.
How it works
The converter treats DPI and PPI as numerically identical (both express dots or pixels per 25.4 mm inch), converts the input to dots per inch, then divides by the appropriate length ratio to reach DPCM or DPMM. The only arithmetic involved is scaling by powers of the inch-to-centimetre or inch-to-millimetre ratio.
Common mistake: DPI (dots per inch, a print term) and PPI (pixels per inch, a screen term) are technically distinct concepts — DPI refers to physical ink dots laid down by a printer, while PPI refers to pixels on a display — but they share the same numeric scale and this converter treats them as equivalent, which is appropriate for most resolution-comparison purposes.
Worked example
Convert 300 DPI to PPI, DPCM, and DPMM
- Start with input: 300 DPI.
- Base in DPI: 300 × 1 = 300.
- PPI = 300 / 1 = 300.
- DPCM = 300 / 2.54 ≈ 118.11; DPMM = 300 / 25.4 ≈ 11.811.
300 DPI = 300 PPI, 118.11 DPCM, 11.811 DPMM.
Common mistakes to avoid
- Treating DPI and PPI as always equivalent -- DPI (dots per inch) refers to printer output resolution while PPI (pixels per inch) refers to screen pixel density; they are numerically equal in this converter but describe different physical phenomena.
- Assuming a higher DPI image will look better on screen -- monitors display at their native PPI regardless of an image file embedded DPI metadata; DPI only matters when printing.
- Confusing screen resolution (total pixels, e.g. 1920x1080) with pixel density (PPI) -- two screens can have the same total resolution but very different pixel densities depending on physical size.
Key terms
- DPI (dots per inch)
- A print resolution metric counting the number of individual ink dots a printer places within one linear inch. Higher DPI means finer detail in printed output.
- PPI (pixels per inch)
- A display resolution metric counting the number of pixels within one linear inch of a screen. Higher PPI yields sharper-looking images on screen.
- DPCM (dots per centimetre)
- A resolution metric used in contexts where metric length units are preferred; 1 DPCM = 2.54 DPI, since there are 2.54 cm per inch.
- DPMM (dots per millimetre)
- A fine-scale resolution metric, commonly used in industrial printing and barcode standards; 1 DPMM = 25.4 DPI.
Frequently asked questions
- What DPI should I use for printing photos?
- 300 DPI is the standard for high-quality photo prints. At 300 DPI, an 8x10 inch print requires at least 2400x3000 pixels. Below 200 DPI, pixelation becomes visible at normal viewing distances.
- Does a higher screen PPI always mean a better display?
- Above about 300 PPI at typical viewing distances (phone) or 200 PPI (monitor), the human eye cannot distinguish individual pixels. Beyond those thresholds, higher PPI yields diminishing perceptual returns, though it can improve sub-pixel text rendering.
- What is DPCM used for?
- DPCM (dots per centimetre) is the metric equivalent of DPI used in some European and ISO printing standards. 1 DPCM = 2.54 DPI; a standard 300 DPI print is about 118 DPCM.