Print resolution
Pixels,
centimetres,
300 DPI.
Four calculators, free, no account, no upload. Every number is worked out by your own browser, and every formula is written out so you can redo it by hand.
DPI converter
Change a file's
DPI tag
Drop it, pick the density, download. Milliseconds, no upload, no re-encoding: the file comes out at the exact weight it went in.
Convert →DPI calculator
Pixels ↔ centimetres
at 300 DPI
Both directions. The print size your file allows, or the pixels a given size demands, with a verdict on every format print shops actually sell.
Calculate →Checker
Check a file
in one second
Drop an image: real pixel size, the DPI tag read straight from the JFIF, EXIF or pHYs header, and the largest print it holds. Nothing leaves your machine.
Drop a file →Converter
Pixels, cm,
mm, inches
Four units tied to the density you choose, plus the ISO and US paper sizes in pixels at 300, 150 and 72 DPI.
Convert →Megapixels
How big can
you print it
Megapixels needed for A4, A3, 24 × 36 inches, and how far viewing distance lets you drop below 300 DPI.
Calculate →The three formulas
Pixels needed
inches × 300
A 12 inch wide print needs 3600 pixels.
Size you can reach
px ÷ 300 × 2.54
A 4000 pixel file prints 33.9 cm, or 13.3 inches.
Crop loss
1 − r₁ ÷ r₂
Square into 3:4 throws away a quarter of the image.
Two things worth knowing before you calculate
The DPI tag in your file is not quality
It is two bytes in the header. A file labelled 72 DPI prints a 24 inch poster without complaint if it has the pixels. What changing it actually does.
300 DPI is a safety margin, not physics
The eye resolves about 5 line pairs per millimetre at 25 cm. A framed print viewed at one metre only needs 150 to 200 DPI, which doubles the size you can print. Print-on-demand platforms ask for 300 because they do not know how far away your buyer will hang it.
Not enough pixels?
The workshop upscales with a neural network inside your browser and writes a 300 DPI file in a size print shops sell. Its interface is in French for now.