Paint Calculator
Estimate wall and optional ceiling paint from room dimensions, openings, coats, coverage, primer, can size, and price.
Paint quantity starts with net wall and ceiling area, then divides by the product’s stated coverage per coat. Doors, windows, coats, primer, surface texture, and can size determine what you should actually buy.
301 sq ft, 2 coat(s), 1.69 gallons after allowance.
- Finish paint2 1-gal cans
Coverage varies with texture, color change, application method, and product. Use the can label when it differs.
Step by step
- 1
Enter room dimensions and remove only doors or windows large enough to materially affect the estimate.
- 2
Use the coverage printed on the chosen paint and set the real number of finish coats and primer coats.
- 3
Round up to available can sizes and keep enough of the same batch for touch-ups when color consistency matters.
Check the estimate before you buy
Estimate wall and optional ceiling paint after subtracting standard doors and windows, selecting coats, coverage, can size, primer, and cost.
A 12 × 10 ft room with 8 ft walls, one door, two windows, and two coats has about 301 sq ft of net wall surface. At 375 sq ft per gallon, two coats require about 1.61 gallons before allowance.
How the calculation works
The calculator multiplies room perimeter by wall height, subtracts openings, adds the ceiling when selected, then multiplies by coats and divides by the coverage on the can.
Paint Calculator FAQ
Should I buy exactly the calculated amount of paint?
Usually no. Cuts, spillage, breakage, uneven surfaces, batch matching, and package rounding can increase the order. Use the editable allowance and confirm the product label.
Why does the result round up?
Stores sell full bags, boxes, cans, rolls, panels, or pieces. The tool keeps the mathematical amount visible, then rounds the purchasing quantity up separately.
Does the calculator subtract doors and windows?
Yes. Each standard door and window subtracts a planning allowance. For unusually large openings, calculate the net wall area separately.
Is 350–400 square feet per gallon guaranteed?
No. It is a common planning range, but texture, porosity, application, color, and product can change coverage.
Reference: HomeTaskKit material-estimating method. Results are practical estimates; complete labels, package directions, product specifications, and qualified professional advice take priority.