What you need
- A tape measure or laser measure
- A phone or notepad for recording measurements
- The room length, room width and wall height
- The number of doors and windows
Measure in four simple steps
Measure the room length
Measure the longest wall from one corner to the other. Keep the tape straight and record the number.
Measure the room width
Measure the shorter side of the room from wall to wall.
Measure the wall height
Measure from the finished floor to the ceiling. If the height changes, use the greatest height for a safer estimate.
Count doors and windows
For a quick estimate, enter the number of standard doors and windows. The calculator deducts a standard area for each one.
Metric: enter measurements in metres. For example, 350 cm is 3.5 m. Imperial: enter measurements in feet. For example, 6 inches is 0.5 ft.
Before buying paint
The calculator includes 10% extra for normal waste and touch-ups. Real coverage can still change with the paint product, wall texture, surface preparation and application method. When available, compare the result with the coverage printed on the paint label.
If a room is not rectangular, divide it into simple rectangular areas, calculate each section separately and add the results.
For additional product-specific guidance, see the Sherwin-Williams paint calculator guidance and Behr interior paint measuring guide.