Why the paint coverage calculator matters
Paint quantity is a coverage problem, not an area problem: two coats on a porous surface can use nearly double what the tin claims. This page turns that decision into a handful of inputs you can defend in a budget review: volume, unit cost, rate of adoption, and time. The output is a planning baseline, not a promise — it tells you whether the idea deserves a vendor quote, a pilot, or a pass.
- • Biggest swing factor: the total wall area across all walls
- • Second-order factor: the coverage per gallon for your surface
- • Often ignored: the number of coats, which multiplies everything
What actually changes the answer
the total wall area across all walls moves this number first, then the coverage per gallon for your surface. Run a conservative case and an upside case before you commit. If the maths only works in the upside case, treat it as a time-boxed test with a kill date rather than a line in next year's plan.
What to do with the result
Halve the coverage figure for the first coat on new drywall or a strong colour change.
FAQ
What does the paint coverage calculator work out?
It applies Area = length × width; Adjusted = area × (1 + waste%); Units = ceil(adjusted ÷ coverage per unit); Cost = units × unit price to the values you enter for total wall length (ft), wall height (ft), coverage per gallon (sq ft), price per gallon, extra allowance for touch-ups. Paint quantity is a coverage problem, not an area problem: two coats on a porous surface can use nearly double what the tin claims.
How accurate is this paint coverage calculator?
Single-coat estimate. Multiply the result by the number of coats you plan, and subtract large windows and doors from the area. Replace the defaults with your own invoice, usage export, payroll data, statement, or vendor quote before making a commitment — the maths is exact, so the answer is only as good as the inputs you feed it.
Which input should I stress-test first?
the total wall area across all walls. Re-run with a pessimistic value for it; if the decision flips, that assumption is the thing you need real data on before signing anything. After that, check the coverage per gallon for your surface and the number of coats, which multiplies everything.
Which scenario should I start from?
Start with the preset closest to your situation — tight estimate, standard job, complex layout — then edit the sliders. Presets are realistic starting points, not benchmarks to match, and every change updates the result instantly.
What should I do after running the numbers?
Halve the coverage figure for the first coat on new drywall or a strong colour change. A useful planning benchmark to compare against: A gallon of interior paint covers roughly 350–400 sq ft per coat.
Can I share or save this calculation?
Yes. Your inputs are written into the page URL, so copying the link shares the exact scenario you are looking at — the person who opens it sees the same numbers. You can also export the inputs and results to CSV or PDF from the result card and keep it with the rest of your workings.
How this calculator is built
Independently maintained
Written by Sam Doshi and the RevenueLab editorial team. We don't sell the data feeds this tool is built on.
Sourced from primary data
Benchmarks come from public AdSense / Stripe / IRS disclosures and reader-submitted data — never third-party "$X per view" claims. Full methodology.
Last editorial review
Reviewed on a rolling quarterly cycle. Dated reviews are published on the methodology record for each calculator.
Editorial standards
See our editorial policy and disclaimer. Results are estimates, not advice.