- First, assess the size of the area that you’re painting. Grab a friend to help measure the width and height of the walls with a tape measure; multiply these together to get the overall surface area.
- Length of Wall X Height of Wall = Total Wall Surface to be Painted
- Use the above same calculation method to measure the space used by windows and doors, and subtract the result from your overall surface area.
- Multiply your new total surface area by the number of coats you need – we recommend factoring in at least two coats. It's also worth including a little extra paint for touch ups.
- Finally, divide this total figure by the m²/l number on your paint tin (if you can’t see it on the tin, look for it online at the product information section). This will give you the total litres of paint you need for your project.
It is a good idea to utilise a Paint Calculator to determine how much paint you will need, however there are some other things to take into consideration when determining the quantities of paint you should have handy for your painting project:
- Take the texture of the wall you will be painting into account. Highly porous surfaces will absorb quite a considerable amount of paint, as will decorative surfaces like rough cast, embossed papers and textured coatings. Even during priming you may have to use more product than you had originally intended – sometimes up to double the amount.
- You must also work out how many times you will need to apply the undercoat. If you are covering up a very strong, dark colour then you can ask your paint and hardware store to add some black to your universal white undercoat. This will create an undercoat that is light grey in colour, which will cover the darker colours more effectively without you needing to apply multiple layers.
- If you are painting external surfaces, you should always allow for at least two topcoats to ensure that the surface has good protection against the elements.