Paint coverage calculator
Find out how much paint to buy for a room, based on wall area, number of coats, and your paint's coverage rate.
Don't subtract doors and windows unless they're large — most painters just round up slightly instead.
Fill in the fields and press Calculate to see your result here.
How this calculation works
Total paint needed is wall area × number of coats, divided by how much area one gallon (or liter) covers — that coverage rate is usually printed on the paint can, and varies by paint type and wall texture (a textured or very porous wall needs more paint per coat than a smooth one).
Tips
Check the can for your specific coverage rate
350 sq ft per gallon (about 10 m² per liter) is a typical default, but the actual number varies by paint brand, sheen and the wall's texture — the can label is the most accurate source.
Round up to the next full can
Paint is sold in fixed can sizes, so round your total up rather than trying to buy the exact fractional amount.
Subtract doors and windows
Deduct large openings from the wall area to avoid buying paint you won't use.
Dark to light needs more coats
Covering a dark colour with a light one often takes primer or an extra coat.
Ceilings are separate
Calculate ceiling area on its own, as it often needs a different paint.
Frequently asked questions
Should I subtract the area of windows and doors?
For a small number of standard doors and windows, most people just round up rather than subtracting — it's a small margin and having extra paint on hand for touch-ups is convenient.
Does primer use the same coverage rate?
Primer coverage can differ from topcoat paint — check the primer can's own coverage rating rather than reusing your topcoat's number.