How to calculate the pixel ratio from millimeters

In our product lists we always work with millimeter sizes instead of pixels. We have decided to work this way so you can decide for yourself how large the image will be. We will always calculate it back to the size we need to print and don’t really mind what we receive from you. Of course we do have a recommendation, use 300 DPI as this is what our printers run by default.

Most designers can work with millimeter sizes but sometimes partners do request a size in pixels. It’s easy to calculate if you know the math.

How to do the calculation?

To calculate the number of pixels you need two things:

  • A width and height in millimeters
  • The amount of pixels in that width/height

The calculation is as follows:

(Width in millimeters / millimeters in an inch) * 300 pixels per inch

An example calculation

Width: 60 millimeters

(60 / 25.4) * 300 = 709 pixels

Height: 152 millimeters

(152 / 25.4) * 300 = 1795 pixels