Paint calculator
This paint calculator works out how much paint your room needs: enter the room size, doors and windows, the number of coats and your paint's coverage – and get the right can sizes too.
Source: Wikipedia – Hiding power. Updated: .
How it is calculated
A 15 × 12 ft room with 8 ft ceilings, one door and two windows has about 380 ft² of wall and needs roughly 2.4 gallons for two coats at 350 ft² per gallon. The paint calculator takes your measurements and shows the amount and can sizes.
How it is calculated
- Wall area: perimeter × ceiling height, minus doors (about 21 ft²) and windows (about 15 ft²).
- Ceiling: length × width, if you paint it too.
- Paint amount: area × number of coats ÷ coverage. The manufacturer gives the coverage per gallon or liter; hiding power is tested to the EN 13300 standard at that coverage.
- Extra: ten percent more covers losses on the tray, roller and edges.
Finally the tool looks for the can combination with the least surplus, for example 2.5 gallons for a need of 2.4. Very porous surfaces such as fresh plaster often need a primer and more paint; dark walls a third coat.
More calculators for renovating: wallpaper calculator, square footage calculator, laminate and tiles.
Frequently asked questions
How much paint do I need per square foot?
At a coverage of 350 ft² per gallon and two coats, about 0.0057 gallon (0.73 fluid ounces) per square foot of wall. The exact coverage is printed on the can.
How do I work out the wall area of a room?
Perimeter of the room (2 × length + 2 × width) times ceiling height, minus doors and windows. The calculator does this and deducts 21 ft² per door and 15 ft² per window.
How many coats are needed?
Usually two. On dark or strongly patterned surfaces or when changing color a third coat may be needed.
Should I add the ceiling separately?
Choose “Yes, walls and ceiling” and length × width is added. Many people use a separate ceiling paint; the amount is worked out the same way.
Why add extra paint?
Some paint stays on the roller and brush, and edges and rough spots take more. Ten percent is a common buffer, and leftovers are good for touch-ups.
Sources and legal basis
As of: · Editorial policy
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