How much paint do you need?
Paint coverage is usually about 10–12 m² per litre (roughly 350–400 sq ft per gallon) per coat. This calculator takes your wall area, subtracts a standard allowance for each door (about 1.8 m²) and window (about 1.4 m²), multiplies by your number of coats, and adds a small buffer for touch-ups.
Tips for an accurate estimate
Dark or drastic colour changes often need an extra coat. Fresh plaster and bare wood soak up more paint, so add 10–15%. When in doubt, one extra tin is cheaper than stopping the job to buy more.
Frequently asked questions
Does this include the ceiling?
No — this estimates walls only. Calculate the ceiling separately using its floor area × your paint's coverage.
How many coats should I use?
Two is standard for good coverage. Use three when going from a dark colour to a light one, or on very porous surfaces.