PreConstruct AIFree calculator
Paint calculator — finish and primer, in cans and pails
Type the wall length and height, take off the openings, add a ceiling, set the coats and the coverage from the product data sheet. Get cans, litres and pails, with the working.
Finish paint
7 cans
24.57 L needed
Primer
5 cans
16.38 L needed
Area
1,300 SF
120.77 m²
Pails instead
1 × 18.9 L
+ 2 cans
The working
- walls 160 LF × 9 ft − openings 140 SF = 1,300 SF
- finish 1,300 SF × 2 coats ÷ 400 SF a can = 6.5 → 7 cans
- primer 1,300 SF × 1 ÷ 300 SF a can = 4.33 → 5 cans
A starting figure, not an engineered quantity. Sizes, reinforcing and code requirements come from your drawings, your specifications and your engineer — check them before you order.
Where a calculator stops
This does one run, from numbers you type. A bid is every run on every sheet.
- — It doesn't read the drawing set or its schedules
- — It doesn't measure on the PDF or keep the lengths
- — It doesn't show what an addendum changed
- — It doesn't price, add labour or build a proposal
Area
Room perimeter × height, less doors and windows, plus the ceiling if it is in your scope. A common allowance is about 21 SF a door and 15 SF a window when the schedule gives no size.
Coverage and coats
SF × coats ÷ SF per can. Premium interior paints often list about 400 SF (37 m²) per 3.78 L on smooth, primed drywall, and primers less; the data sheet for the product specified is the source. New drywall usually takes a primer and two finish coats; rough or porous surfaces take more paint.
Cans or pails
In Canada a “gallon” can is 3.78 L and a pail is 18.9 L — five cans. On larger jobs, buy pails and top up with cans.
Questions estimators ask
- How much paint do I need for 1,000 square feet?
- At 400 SF per 3.78 L and two coats, 2,000 ÷ 400 = 5 cans, or one 18.9 L pail. Coverage varies by product and surface, so use the data sheet.
- How many coats on new drywall?
- Usually one coat of drywall primer and two finish coats. The specification on the drawings or the finish schedule governs.
- How big is a gallon of paint in Canada?
- Paint sold as a gallon in Canada is 3.78 or 3.79 litres, the US gallon. A pail is 18.9 L.
- Should I subtract doors and windows?
- Yes, from the wall area. Keep them in if you are also painting the frames or the doors themselves — those are separate lines.
Stop retyping sizes into a calculator
On PreConstruct AI you measure on the PDF, type the sizes the drawings print, and the concrete, forms, bars, board and stringers come out with the arithmetic beside every line — in imperial, metric or both. Your first bid is free, with no card.