How To Calculate How Much Paint You Need For Your Next Decorating Project

January 8th, 2024

Not sure how much paint you’re going to need for your decorating project? We have got you covered! With some easy measurements and simple calculations, you’ll be skipping to your local Brewers Decorator Centre ready to buy your perfect finish.

Step 1: Measure your room.

Grab a tape measure and measure the height and width of each wall you would like to paint. Multiply both of these measurements and you’ll get your square metre measurement. Measure any windows and doors within the room, complete the same calculation and subtract from the total square metre measurement.

For example:

  1. The feature wall I want to paint is 2.5m x 3m, giving a total of 7.5sq/m. If you are painting the whole room, don’t forget to measure all 4 walls and add together!
  2. There is a window measuring 1m x 1m (1sq/m) and a door measuring 1m x 2m (2sq/m) making a total of 3sq/m.
  3. Subtracting 3sq/m  from 7.5sq/m gives a total of 4.5sq/m which is the total square metre measurement.

Step 2: Don’t forget your coats!

We always advise using 2 coats when painting walls for the best results. Multiply your square metre measurement by the number of coats you want to apply (2) to find out your total paint coverage.

For example:

My total square metre measurement is 4.5sq/m which can be multiplied by 2, creating a total paint coverage of 9sq/m.

Step 3: Calculate how many litres of paint you need.

Find your finish’s coverage information. This information can be found on all of our product pages. Divide your total paint coverage by the square metre per litre of the paint finish to find out how many litres of paint you need. Most paint finishes are available in 1L, 2.5L and 5L.

For example:

Albany Durable Matt has a coverage of Up to 14sq/m per litre. Dividing 9sq/m by 14sq/m gives you a grand total of 0.6L.

Top tip: if you are using tinted product, make sure you order enough to complete the job and ensure consistent colour. There can be minor discrepancies in paint batches when mixing at different times (or at different stores).

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