How much paint do I need?

To determine how much paint you need for your project you will need the following information:

1. Surface area of the surface(s) to be painted (excluding areas where there are windows, doors etc).

2. Spreading rate of the paint being used.

3. The number of coats required.

Once you have the above information, you can calculate the amount required as follows:

Total surface area (in square metres)

Divided by ÷

Spreading rate of paint (in square metres per litre)

Multiplied by x

Number of coats

Equals =

Total litres required

Porous, rough and textured surfaces (e.g. corrugated iron or rough plaster) will require more paint.

For example

1. To paint the living room walls excluding the ceiling. The walls are 3

metres high, each wall is approx 4 metres in width, and windows and

doors make up approx 0.5 of a metre of each wall leaving a paintable

surface of 3.5 metres per wall. The surface area to paint is therefore 14

metres (4 walls x 3.5 metres each) x 3 metres high = 42 square metres.

2. The walls are currently painted and are in good condition. The product label and data sheet tells us that it has a theoretical spreading rate of 11 square metres per litre. (You can get spreading rate information from the the Product Data Sheet section on the website).

3. As the walls are previously painted and in good condition, only two

coats are required.

The amount of paint required is therefore:

Surface area: 42 square metres

Divided by ÷

Spreading rate: 11 square metres per litre

Multiplied by x

Number of coats: 2 coats

Equals = 42/11 x 2 = 7.6 litres

This tells us that 7.6 litres of paint is required to paint two coats onto the living room walls. The best idea would then be to purchase 8 litres giving enough paint to complete the job and sufficient to go back if touch up is required later.

To get a rough idea of how much paint you will approximately need when you only have house plans to work from, use the following calculations;

Look for the statement of area on the house plans, e.g. 186m2

Divide this by

÷ 10 = litres of sealer for ceilings

÷ 5 = litres of 2 coats for ceilings

÷ 4 = litres of sealer for walls

÷ 2 = litres of 2 coats for walls

÷ 25 = litres of primer for trim/doors/frames

÷ 15 = litres of 2 coats for trim/doors/frames

This quick estimate works as a general guide for most houses, but extreme designs or colour palettes tailored to each room will need a more careful approach with each room calculated individually.

Most suppliers have paint calculators on their websites, specifically designed to calculate the amount of paint needed considering the spread rate per product.