Quick answer
Convert paintable square footage and coat count into gallons using a product-specific coverage rate. 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
700 coat-ft² at 350 ft² per gallon equals 2 gallons before allowing for surface texture and touch-ups.
Common uses
- Interior walls
- Ceilings
- Exterior walls
- Primer planning
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.
Paint Gallon Calculator FAQ
How many square feet does a gallon cover?
Many products publish a range around 350–400 ft² per gallon, but use the exact label because substrate and application change real coverage.
Do two coats double the paint?
For planning, multiply the paintable area by the number of coats. Actual second-coat usage may vary, but this is a transparent starting point.
Can I mix gallon and quart sizes?
Yes. After estimating total volume, compare available container sizes to reduce unnecessary leftover paint.