Quick answer
Estimate whole-house paint quantity by combining wall areas and applying separate coat and coverage assumptions for each surface type. Use the working RenoMetric calculator below for the actual estimate, then use this page to check assumptions, package rounding and project-specific considerations.
Open the working Paint calculator
Formula
Worked planning example
For a whole-house plan, calculate rooms or exterior elevations separately, then total gallons by paint product and finish.
Common uses
- Whole-home interiors
- Rental repainting
- Exterior repainting
- Pre-purchase budgeting
How to get a better estimate
Measure the actual project rather than relying on listing dimensions. For irregular spaces, split the surface into simple measurable sections and add the results. Use the exact product label for package coverage, yield, density or square-foot coverage whenever it is available.
Keep waste and package rounding as separate steps. Waste covers cuts, breakage, pattern matching and unavoidable offcuts. Package rounding reflects the fact that many materials are sold only in complete bags, boxes, bundles or cans.
Before you buy: this page is a planning guide, not a contractor quotation or structural design. Verify final quantities with the product manufacturer, supplier or installer when project conditions could materially change the result.
House Paint Calculator FAQ
Should every room use one coverage rate?
Only when the same product and similar surface conditions apply. Separate calculations are better when finishes or products differ.
How do I include trim?
Trim is often easier to estimate separately using linear measurements or a dedicated trim-paint allowance.
Does the calculator replace a contractor quote?
No. It is a material-planning tool. Access, repairs, prep work, labor and site conditions can dominate a professional quote.