Estimate paint for walls, ceilings, one or multiple rooms, or a known area using editable coats, product coverage, deductions, container size, primer, and material price.
For a rectangular room, wall area is perimeter multiplied by height. Ceiling area is length multiplied by width and is included only when selected.
All dimensions are normalized before area calculations. Coverage is normalized to square meters per liter, and paint volume is stored internally in liters before being displayed as gallons or liters.
2 × (room length + room width) × wall height × quantityroom length × room width × quantitydoor/window width × height × quantitygross area − all deductionsnet area × number of coatscoverage-required area ÷ product coverage rateceiling(required volume ÷ selected container volume)purchased container volume − required volumeA 12 ft × 10 ft room with 8 ft walls has 352 ft² of wall area. Two coats require 704 ft² of coverage. At 400 ft² per gallon, this is 1.76 gallons, so buy two 1-gallon cans.
The same room minus one 3 × 7 ft door and two 3 × 4 ft windows has 307 ft² net area. Two coats require 614 ft², or 1.535 gallons at 400 ft² per gallon.
A 5 m × 4 m room with 2.5 m walls has 45 m² of wall area. Two coats at 10 m²/L need 9 L. Two 5 L containers provide 10 L, leaving about 1 L.
Surface texture, porosity, application, and paint product affect coverage. The editable default is a planning value, not a guarantee.
The default is two coats, but the appropriate number depends on the surface, color change, product, and preparation.
Select an actually available container size. The calculator uses deterministic upward rounding rather than assuming a retailer's product mix.
No standard door or window sizes are assumed. Enter actual opening dimensions and quantities. Ceilings are excluded unless selected for each room.
The optional primer estimate has independent coats, coverage, container size, and price. Paint and primer coverage are never assumed to match.
US gallon and quart conversions use the shared volume system. Container rounding naturally creates extra purchased paint; the optional extra percentage remains separate and defaults to zero.
Optional prices are per selected paint or primer container. Estimates exclude labor, brushes, rollers, tape, drop cloths, repairs, taxes, and delivery.
Calculate wall and optional ceiling area, subtract openings, multiply by coats, and divide by the product coverage rate.
Add room length and width, multiply by two for perimeter, then multiply by wall height.
Coverage varies by product and surface. Enter the manufacturer's rate; the US default of 400 ft²/gal is editable.
Enter actual openings that will not be painted; nothing is subtracted automatically.
Use the number appropriate to the product, surface, color change, and project. The editable default is two.
Select Include ceiling for a room; its length-by-width area is added before coats are applied.
Multiply net area by two, then divide by the paint's square-foot-per-gallon coverage.
The shared conversion uses exactly 3.785411784 liters per US gallon.
Texture, porosity, preparation, application method, color change, and product formulation can affect coverage.
Required volume is divided by your selected container size and rounded upward.
Estimated leftover is purchased container volume minus calculated required volume.
Yes, when enabled, primer is calculated separately with its own settings.
No. Optional pricing covers paint and primer containers only.