Paint Calculator
Enter your room dimensions and the calculator subtracts openings, applies your chosen number of coats and returns the gallons to buy — rounded up, because paint is sold in whole cans.
- Paintable wall area
- 417 sq ft
- Primer (1 coat)
- 2 gal
- Estimated paint cost
- $144
- · Openings are subtracted using standard sizes — adjust the count if your doors or windows are unusually large.
- · Buy one extra quart for touch-ups from the same batch; colour drifts between batches.
How to use the Paint Calculator
-
01
Measure the room length, width and wall height in feet.
-
02
Count doors and windows, then choose the number of finish coats.
-
03
Check the paint tin for its coverage rate and enter the current price.
-
04
Use the rounded-up gallon figure for your order and keep the area figure for comparing quotes.
Frequently asked questions
Does this include the ceiling?
No. The result covers the room walls only. Calculate the ceiling separately using length multiplied by width.
Do I always need primer?
Use primer on bare drywall, repairs, stains, glossy surfaces or a major colour change. Sound painted walls may not need it.
Why does the calculator round up?
Paint is normally sold in whole cans, and a small reserve helps with cutting-in and future touch-ups.
Other tools
Flooring Calculator
Boxes of flooring needed for any room, with a waste allowance for cuts and pattern.
Tile Calculator
Tiles, grout and adhesive for floors or walls, with breakage allowance.
Wallpaper Calculator
Rolls of wallpaper needed, accounting for pattern repeat.
AC & Heating BTU Calculator
Estimate the cooling capacity a room actually needs.
These calculators give planning estimates based on the figures you enter. They are not a substitute for a site survey, a structural or load calculation, or professional advice. Always confirm quantities with your supplier or contractor before ordering.