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DPI & Print Size Calculator

Work out how big an image prints at a given DPI, how many pixels you need for a print size, or the effective DPI of an image at a size — in inches, centimetres or millimetres. Includes a quality guide for photo prints and posters.

This tool runs entirely in your browser.

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How to use the DPI & Print Size Calculator

  1. 1Choose what to calculate: print size, the pixels needed, or the DPI of an image at a given size.
  2. 2Enter the known values and pick inches, centimetres or millimetres.
  3. 3Read the result, the formula used and the print-quality guide.

What is the DPI & Print Size Calculator?

DPI (dots per inch) — strictly PPI, pixels per inch, for digital images — links pixel dimensions to physical size: inches = pixels ÷ DPI, and pixels = inches × DPI. A 3000 × 2000 pixel photo printed at 300 DPI is 10 × 6.67 inches (25.4 × 16.9 cm); at 150 DPI it prints twice as large but half as sharp.

The DPI number stored in an image file changes nothing about the image itself — it only tells software what size to print it by default. More pixels mean more detail; a higher DPI setting on the same pixels just makes the print smaller. As a guide, 300 DPI looks sharp in the hand, 150–200 DPI is fine for posters viewed from a metre or more, and large banners viewed from far away can go lower. Upscaling a small image adds pixels but not real detail.

In-depth guide

DPI Explained: How Big Can You Print Your Photo? →

Frequently asked questions

What DPI do I need for printing?

300 DPI for photos and documents you hold close, 150–200 DPI for posters, and less for large banners seen from a distance. Many print shops ask for 300 DPI at the final size.

How many pixels do I need for an A4 print at 300 DPI?

A4 is 210 × 297 mm (8.27 × 11.69 in), so about 2,481 × 3,508 pixels. Choose “Pixels needed”, enter 210 × 297 mm and 300 DPI to check.

Does changing the DPI make my image sharper?

No. Changing only the DPI value changes the default print size, not the detail. Sharpness depends on the number of pixels and on how large you print them.

Is the DPI & Print Size Calculator free and private?

Yes. The DPI & Print Size Calculator is free, needs no account, and runs entirely in your browser. What you type is never sent to a server or stored.

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