PPI describes how many image pixels are assigned to each printed inch. DPI describes dots in an output process, such as a printer’s ink dots. They are sometimes used interchangeably, but do not measure the same thing.
Which number belongs in the calculator?
For a 2,400-pixel-wide photo printed at 8 in (20.32 cm), effective resolution is 2,400 ÷ 8 = 300 PPI. A printer’s advertised ink DPI is not the value needed to calculate this image size.
Do I always need 300 PPI?
300 PPI is a common reference for some print work, not a certification. Suitable resolution depends on content, process and viewing distance. Changing the number does not make a blurred photo sharp.
Compare scenarios in the print size calculator. Inspect the actual image rather than pursuing a number by itself.
Check in your software
- Actual pixel width and height.
- Intended physical size, in inches or centimetres.
- Whether changing resolution also resamples the file.
- Whether export or printing applies another scale.
The tool does not modify an image or assess its detail. Vector artwork has different export considerations; a pixel calculation applies to a raster image.
References and scope
The numerical examples are our own. Check a physical print on your own equipment.