You’ve decided on the colour and the finish, but how much paint do you actually need?

If you buy too little paint you will end up having to pop out for more, but if you buy too much, you will have a lot of unnecessary waste and cans needing storage.  So how do you get it just right?


Grab a tape measure and work out the height and width of the surface you want to paint.  Then multiply the height and width together.  This will give you the square metre measurement, basically the area you want to paint.  Subtract the sizes of any windows and doors from the total area using the same calculation.

Number of coats

Depending on the colour and the surface you are painting, it is always advisable to expect to apply two coats of paint.  This means you should multiply your area (see previous point) by two (the number of coats).  You will now have the final amount of paint you require, you just need to convert this into the number of cans needed.

Number of paint cans

Check the paint cans to see square metre coverage per litre and use this to calculate how much you need to buy.  Don’t just plump for two large cans of paint if you’re just over the coverage recommendations, consider buying one large and one small one as it might be more cost effective and there will be less waste.  You can use any leftover paint for touch ups however.

Skirting boards and trim

Much like walls, you can calculate the amount of paint required in the same way.  Measure the length of the skirting and any windows and trim to calculate the area per square metre.

Painting a door

As a general rule most doors are around 2 metres tall and under 1 metre wide, equalling a 2 metre square area to paint.  So you will have more than enough if you buy 1 litre of paint to achieve two coats.