roller with grey paint

How To Work Out How Much Paint You Need for Any Home Decorating Project

How much paint do I need? Let Dulux show you how to calculate your paint coverage. Estimate the paint needed for woodwork, feature walls and any size room.


How much paint do I need for my project? How many coats of paint are needed? If you’re asking these questions, you’re not alone. Buy too little paint and you end up back and forth to purchase more. Buy too much and you end up with cans stacked up in the shed (although this could be useful for touch ups!) If only such thing as a paint calculator existed, eh? Well, you’re in luck, because we’re here to show you just how simple it can be to calculate the paint you need with just three easy steps, no guesstimates necessary. 

dulux woman painting

Step 1 - Measure up

First off, you need to grab a tape measure to work out the height and width of the surface you want to paint. Then, multiply the height and width together to get your square metre measurement. Subtract any windows and doors by using the same calculation method and deducting it from the total.

Step 2 - Calculate your coats

This is where we answer your how many coats of paint query

Step 3 - Divide and conquer

Finally, divide the number by the square metre per litre listed on your paint tin or in the online product information. And there you have it, you’ve worked out the amount of paint you need.

dulux paint brush

I’m already in-store, how much paint do I need?

Do not fret! If you don’t have the measurements of the space you’re painting to hand, but you need to purchase that paint, we’ve put together a handy paint estimator.

Roller Tester
Enough for a small patch on a wall

Interior Wood and Metal
A 750ml tin is perfect for a door or the skirting in a small room

Feature Wall
A 1 litre tin will be ideal to paint a 2.5m interior wall

Small Room
Around 2.5 litres would cover all walls in a 2m x 2m or equivalent room

Medium Room
You’ll need about 5 litres to cover all walls in a 4m x 4m or equivalent room 

paint roller emerald glade

How much Paint is needed ?



3 Rooms

4 Rooms

5 Rooms

Bedroom (Each)

5 litre Can – Qty 1

5 litre Can – Qty 1

5 litre Can – Qty 1


5 litre Can – Qty 1

5 litre Can – Qty 2

5 litre Can – Qty 2

All Ceilings

5 litre Can – Qty 3

5 litre Can – Qty 3

5 litre Can – Qty 4

Formula for Paint Calculator


Measure the length of all walls of the room, and add them together. Then measure the height of the room, and multiply the two measurements. For example, if the room is 4 metres wide, and 6 metres long the total measurement will be 20 metres. Multiply this by the height of the room, i.e 2.5 metres, 20 x 2.5 = 50 square metres. 2 coats will be required, so you will need enough paint to cover 100 square metres. REMEMBER- measure any windows or doors, to remove this from your measurement, which will reduce the amount of paint required.


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