Print Size and DPI Calculator
Print size = pixels ÷ DPI. A 6000 × 4000 pixel (24 MP) photo prints at 20.0 × 13.3 in (50.8 × 33.9 cm) at 300 DPI. A4 at 300 DPI needs 3508 × 2480 pixels (8.7 MP), so this photo fills A4 at 484 PPI.
How to use
- Enter the image width and height in pixels.
- Enter the print resolution: 300 DPI for photo quality, 240 for most inkjet prints, 150 for posters seen from a distance.
- Pick a paper size to see the pixels it needs and the real PPI when the image fills the paper (cropped) or fits inside it (margins). Pixels blend at is the viewing distance where pixels stop being visible, assuming 1 arcminute visual acuity.
How it works
Print size (in) = pixels ÷ DPI. Multiply inches by 2.54 for centimetres.
Pixels needed = paper size (in) × DPI on each side, matched to the image orientation. Megapixels = width × height ÷ 1,000,000.
Real PPI when filling the paper = the smaller of (pixel width ÷ paper width) and (pixel height ÷ paper height); the other side is cropped. Fitting without cropping leaves margins and gives the larger value.
Viewing distance where single pixels stop being visible ≈ 3438 ÷ PPI inches, assuming normal 1 arcminute visual acuity. This is an estimate, not a lab standard.
FAQ
Is DPI the same as PPI?
Strictly, PPI is image pixels per inch and DPI is printer ink dots per inch. In practice "300 DPI" for a photo means 300 image pixels per inch, which is what this tool uses.
What resolution do I need for a good print?
Use 300 PPI for photos and documents viewed in the hand, 200 to 240 for larger prints, and 100 to 150 for posters and banners viewed from a few feet. The quality grade here is a rule of thumb, not a printer specification.
How many pixels do I need for A4?
At 300 DPI, A4 (210 × 297 mm) needs 2480 × 3508 pixels, about 8.7 megapixels. At 150 DPI half of each side is enough: 1240 × 1754.
Does changing the DPI setting in an image editor change quality?
Not by itself. Changing the DPI tag without resampling only changes the default print size. Quality depends on the pixel count and how large you print.
Why does my photo not fill 8 × 10 exactly?
Most cameras shoot 3:2 or 4:3, while 8 × 10 is 5:4. Filling the paper crops part of the image; fitting it whole leaves white margins.