How to calculate the perfect amount of paint for your walls

A simple formula lets you calculate the precise amount of paint you need for any project, big or small.

Follow these simple steps to help measure up your room and calculate the perfect amount of paint you need for your walls:

Calculating the overall room measurement
Overall room measurement
  1. Width x height of walls
    =Overall room measurement
Calculating overall door and window measurement
Overall door and window measurement
  1. Width x height of doors and windows
    =Overall door and window measurement

  2. Overall room measurement – Overall door and window measurement
    =Wall space to be painted

  3. Wall space x 2 (for two coats) + a little for touch ups
    =Total

  4. Total / m² / l number on your paint tin
    =Number of litres of paint you need for your project

What you’ll need:

Measure up your space to calculate the perfect amount of paint for your walls
Measuring up
  • A metal tape measure
  • A step ladder
  • Pen and paper
  • Calculator

Using the right painting technique will not only mean you achieve a more professional finish but will also help your paint go further: Tips to help you do more with less paint.

Before setting out to buy your paint, have a read of our guide to the ultimate painting tool kit: Our guide to rollers, brushes and extra kit.