Paint Calculator
Estimate theoretical wall-paint quantity from measured room dimensions, openings, coats and the coverage for your exact product.
Enter the room and opening dimensions in feet. Use the coverage printed on the exact paint you plan to buy; the result is a planning estimate, not guaranteed consumption.
Measure your own openings. Surface texture, porosity, color change and application method can change actual coverage; always reconcile the estimate with the product label and available container sizes.
How the paint estimate works
Theoretical gallons = ((gross wall area − measured openings) × number of coats) ÷ coverage printed for the product.
Worked example
Using an 11.5 ft × 13.25 ft room with 8.5 ft walls, one 2.67 ft × 6.67 ft door, two 2.5 ft × 4 ft windows, two coats and 375 sq ft/gal coverage produces a theoretical quantity. The final purchase still has to be rounded to available container sizes.
When this result is useful
Use the result to compare your measured wall area with the coverage information for the exact paint you intend to buy.
Important limitations
Real consumption can change with porosity, texture, color change, application method, overspreading, spills and the condition of the substrate. Coverage values should come from the actual product label or technical data rather than a universal default.
Editorial note: FixLume calculations are educational planning aids. We show the formula and assumptions so you can check the arithmetic yourself. Product-specific requirements should be verified against the exact manufacturer documentation and applicable local requirements.