Method
How to calculate estimated paint needed
The model estimates four walls and subtracts entered door and window area before applying coats and product coverage.
FORMULAPaint = (wall perimeter × height − openings) × coats ÷ coverage
Worked example
Paint calculator example
A 16 × 12 ft room with 9 ft walls has 504 sq ft of wall area before subtracting openings.
Change one assumption at a time to see what drives the result. The output is an estimate, not a quote, forecast or recommendation.
FAQ
Paint calculator FAQ
Should I round paint quantity up?
Yes. The calculator displays exact need and a rounded purchase quantity.
Does coverage vary by surface?
Yes. Texture, porosity, colour change and application method affect real coverage.
Are ceilings included?
No. Add ceiling area separately or model it as another rectangular surface.