DPI and Print Size Calculator

What to work out

Width, pixels

Height, pixels

Print resolution, DPI

Photo 300, poster 150, banner 72.

Result

Print size50.8 × 33.9 cm
Size in pixels6000 × 4000
In inches20 × 13.33″
Megapixels24
DPI300
Qualityphotographic quality, fine to look at closely

Pixels divided by density

Turns pixels into printed centimetres at a given resolution, and answers the reverse question of how many pixels a given format needs.

A file has no physical size: pixels only become centimetres in combination with a print resolution. The same photograph at 6000 pixels across gives twenty inches at 300 DPI and forty at 150.

Which is where the choice of density comes from: 300 DPI for a print held in the hand, 150 for a poster on a wall, and 72 or less for a banner on a building. The further away the viewer, the fewer pixels per inch are worth printing.

What this calculator shows

The print size in centimetres and inches at your chosen DPI
The reverse: the pixel count a given format needs
A quality verdict — photograph, poster or banner

What to keep in mind

The calculation ignores cropping to format: if the file's proportions differ from the paper's, part of the frame goes under the knife.
Interpolation in an editor adds pixels but not detail, so a file cannot be 'stretched up' to 300 DPI in any meaningful sense.

FAQs

How many pixels for an A4 print?

A4 is 21 × 29.7 cm, or 8.27 × 11.7 inches. At 300 DPI that needs 2480 × 3508 pixels, about 8.7 megapixels.

What does 300 DPI mean?

Three hundred dots per inch — the density at which individual dots stop resolving at arm's length. It is the standard for photographic and commercial printing.

Can I print at a lower DPI?

Yes, if the print will be seen from a distance. A poster at 150 DPI looks excellent from half a metre and a banner at 50 DPI from ten.

Does the DPI tag in a file matter?

The number stored in the metadata changes nothing on its own: only the pixel count matters. DPI comes into play the moment the file goes to a printer.

Worked example

A frame from a 24-megapixel camera

Input: 6000 × 4000 pixels at 300 DPI

Output: 50.8 × 33.9 cm, which is 20 × 13.3 inches

Note: A little over A3. The same file at 150 DPI makes a metre-wide poster that looks flawless from a metre and a half away.

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DPI and Print Size Calculator

Result

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