Quick answer
Estimate gallons of wall paint from wall area, openings, number of coats and the coverage rate printed on the can. 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
Four walls totaling 420 ft², two coats and 350 ft²/gal coverage need about 2.4 gallons before purchase rounding.
Common uses
- Bedrooms
- Living rooms
- Hallways
- Interior repainting
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.
Wall Paint Calculator FAQ
Do I subtract windows and doors?
You can subtract meaningful openings for a tighter estimate, though small openings often offset some cutting and touch-up waste.
How many coats should I plan?
Two coats are common for color consistency, but primer, color changes and product instructions can alter the plan.
What coverage number should I use?
Use the coverage range stated on the exact paint product because texture and application method affect real coverage.