Print Size Calculator (px↔mm↔DPI)

Convert px/mm/DPI. Quickly calculate required pixels for A4/A3, etc.

Overview

Convert between px, mm, and DPI. Quickly find real print size and required resolution for web images.

How to use

  1. Enter any two of px/mm/DPI.
  2. The remaining value is auto‑calculated.

Use cases

  • Find required pixels for A4 prints.
  • Check best resolution for posters.
  • Decide optimal scan DPI.

Tips & knowledge

  • 300 DPI is a common baseline for general printing.
  • For large posters, longer viewing distance allows lower DPI.
  • For the web, CSS pixels rather than real‑world size matter.