Paint Calculator
Measure walls and openings, then enter product coverage to calculate paint and optional primer separately.
Jump to calculatorProject takeoff
Paint to purchase
2 containers
Rounded upward using the selected paint container size.
Based on a 12 ft × 10 ft room with 8 ft walls, one opening, and two paint coats.
- Gross paintable area
- 352 ft²
- Opening deductions
- −21 ft²
- Net paintable area
- 331 ft²
- Paint requirement (2 coats)
- 1.89 US gal
- Paint purchasing quantity
- 2 containers
Show your work
Sum the rectangular wall surfaces.
32.7 m² wall area= 32.7 m²Deduct entered openings from wall area only.
32.7 m² − 1.95 m² openings = 30.75 m²= 30.75 m²No ceiling area was selected.
30.75 m² + 0 m² ceiling = 30.75 m²= 30.75 m²Multiply net paintable area by the selected paint coat count.
30.75 m² × 2 coats = 61.5 m² coat-adjusted area= 61.5 m²Divide coat-adjusted area by the user-entered paint coverage.
61.5 m² ÷ 8,589.84 m²/m³ = 0.00716 m³= 0.01 m³Round upward using the selected paint container size.
round up 0.00716 m³ ÷ 0.003785 m³ = 2 containers= 2 containers
Assumptions & warnings
- Paint coverage: 350 ft² per US gal
- Paint coats: 2
- info: Coverage, porosity, texture, application method, color change, product type, and manufacturer instructions can affect actual material needed. This worksheet uses only the coverage values you enter.
- info: Paint purchasing quantity was rounded upward to whole selected containers.
Technical details, sources & version
- SI and customary length, area, and volume unit definitionsexact definition
Dimensions normalize to metres, areas to square metres, and coating volumes to cubic metres before display conversion.
- Rectangular area relationshipmathematical relationship
Each wall, ceiling, and opening is calculated from two normalized dimensions.
- User-entered door and window deductionsuser configurable assumption
Openings are limited to the applicable wall area and are not deducted from a selected ceiling.
- User-selected ceiling inclusionuser configurable assumption
- User-configured coating coat countuser configurable assumption
- User-entered paint coveragemanufacturer specification
Coverage is product-specific; no universal coverage rate is assumed.
- User-entered paint container sizemanufacturer specification
The calculator uses only the selected container size and does not optimize mixed container combinations.
- User-entered paint container priceuser configurable assumption
Optional cost is based on whole selected containers and no live pricing is used.
- User-entered primer coveragemanufacturer specification
Primer is optional and separately configured from paint.
- User-entered primer container sizemanufacturer specification
- User-entered primer container priceuser configurable assumption
- Whole-container purchasing round-upmathematical relationship
The required coating volume is rounded upward to a whole count of the selected container size to avoid under-ordering.
Normalized net paintable area: 30.75 m²
Paint requirement: 7.16 L
paint-calculator · v1.0.0 · released 2026-08-13
Owner: SolverOrg maintainers · Reviewed 2026-08-13
Method
The engine sums rectangular wall surfaces, deducts openings from walls, optionally adds the ceiling, multiplies net area by user-selected coats, divides by user-entered product coverage, then rounds selected container sizes upward. Primer is a separately configured optional coating.
Worked example
A 12 ft by 10 ft room with 8 ft walls has 352 ft² of wall area. Deducting one 3 ft by 7 ft opening leaves 331 ft². At two coats and 350 ft² per US gallon, the required paint volume is 1.89 US gal before container round-up.
Coverage is product-specific
Use the coverage printed for your selected coating. Surface porosity, texture, application method, color changes, product type, and manufacturer instructions can change actual coverage. This is a planning takeoff, not a product recommendation.
Related tool
Drywall Calculator uses the same kind of room, ceiling, and opening measurements for a sheet-material takeoff.