Paint Calculator: How Much Paint You Need
Work out exactly how much paint to buy for a room, so you do not run out halfway through a wall or waste money on paint you will never use. Enter the room size, the number of doors and windows, and the number of coats, and the calculator gives you the wall area, the paint needed, and the number of tins to buy.
How this calculator works
Wall area is 2 x (length + width) x height. A standard door is counted as 21 sq ft and a standard window as 16 sq ft, and both are subtracted. Paint needed is net area divided by the coverage on the tin, usually about 350 sq ft per gallon (about 10 square metres per litre), multiplied by the number of coats. Always round up to the next whole tin, and allow an extra coat when painting a light colour over a dark wall.
Related guide: How Much Paint Do I Need? A Simple Calculator Guide
Frequently asked questions
How much paint do I need for a living room?
A typical living room of 15 by 12 feet with 8-foot ceilings needs about 2 to 3 gallons for two coats, depending on doors and windows. Measure your own room for an accurate figure.
What is the coverage of a gallon of paint?
Usually about 350 square feet per gallon, but check the tin, because coverage varies by brand, colour and surface.
How many coats of paint do I need?
Two coats for most rooms, for an even and durable finish. A dark wall painted a light colour needs a primer and two coats.
Do I need primer?
Yes, on new plaster, on a dark colour, or on a repaired wall. Primer helps the top coats stick and gives an even colour.