Paint Calculator USA 2026
Estimate how many gallons of paint you need for any room, including doors, windows and the number of coats.
Paint Calculator USA 2026 — the quick answer
Estimate how many gallons of paint you need for any room, including doors, windows and the number of coats.
| Formula | Gallons = (Wall Area − Openings) × Coats ÷ 350 sq ft per gallon |
|---|---|
| Category | Painting |
| Cost basis | 2026 USA averages (USD) |
Output
Planning estimate
Time to use
Under a minute
Last reviewed
2026
Built for
DIYers & trades
Enter your measurements
Results
Paintable wall area
366 sq ft
Gallons required
2.1 gal
Quart cans (if <1 gal)
9
Calculation steps
- 1.Gross wall area = 52 × 8 = 416 sq ft
- 2.Openings = 1×20 + 2×15 = 50 sq ft
- 3.Paintable area = 416 − 50 = 366 sq ft
- 4.Gallons = (366 × 2) ÷ 350 = 2.09 gal
Includes a standard waste allowance. Verify with your supplier before ordering.
What this calculator does
Estimates gallons of paint and primer based on wall area, coats and paint coverage — including deductions for doors and windows.
When to use it
- Repainting a room, exterior wall or fence.
- Comparing coverage between brands.
- Budgeting materials for a whole-home refresh.
Common mistakes
- Buying one coat's worth when two are needed on new drywall.
- Ignoring primer — dark-to-light color changes always need it.
- Forgetting trim, ceilings and closets.
Pro tips
- Most latex paints cover 350–400 sq ft per gallon.
- Buy 10% extra for touch-ups later — colors are matched by run.
- Use a 3/8" nap roller for smooth walls, 1/2" for texture.
What the Paint Calculator works out for your paint job
Estimate how many gallons of paint you need for any room, including doors, windows and the number of coats.
Enter Room perimeter (ft), Wall height (ft), Doors and Windows and the paint calculator returns Paintable wall area, Gallons required and Quart cans (if <1 gal) instantly — no signup, no spreadsheet and no install. Every figure updates as you type so you can test two or three paint scenarios before you commit to an order or a bid.
Paint numbers this page gives you
The output is written for a real supply run: quantities and figures you can hand to a supplier or drop straight into a bid for paint work.
- Paintable wall area — recalculated on every input change.
- Gallons required — recalculated on every input change.
- Quart cans (if <1 gal) — recalculated on every input change.
How to estimate paint step by step
The math behind this page is Gallons = (Wall Area − Openings) × Coats ÷ 350 sq ft per gallon. Nothing is hidden — the formula, the assumptions and the waste allowance are all printed on the page so you can re-check the result by hand.
Worked example: A 12×14 room, 8 ft tall = 52 × 8 = 416 sq ft. Minus 1 door + 2 windows = 366 sq ft. Two coats ÷ 350 ≈ 2.1 gal.
- Measure the paint area or run and write down Room perimeter (ft), Wall height (ft), Doors and Windows.
- Enter the figures above and read the paint result.
- Add the recommended waste allowance before you order.
- Save or download the estimate so your supplier and your crew work from the same numbers.
Paint searches this page answers
Homeowners, DIYers and contractors reach this paint page looking for the same handful of answers. Each of these is answered above with the formula shown:
- Paint calculator
- How much paint do I need
- Paint estimator online
- Paint quantity takeoff calculator
- Free paint calculator app USA
- Paint material calculator 2026
Before you order paint: quick checklist
- Re-measure the paint area once before ordering — a second check is cheaper than a second delivery.
- Keep the stated waste allowance in the order; cuts and breakage are normal on paint work.
- Confirm coverage or unit size with your actual supplier — paint pack sizes vary by brand.
More paint planning tools
Pair this paint estimate with the rest of BuildMate: a full calculator index, an AI planner that turns a plain-English description into a materials list, and step-by-step guides for the trade work itself.
Targeted searches: paint calculator · how much paint do I need · paint estimator online · paint quantity takeoff calculator · free paint calculator app USA · paint material calculator 2026
Get 3 Free Quotes
Compare 3 vetted USA pros for your paint calculator project. Free, no obligation.
Disclaimer: This is a planning estimate produced from the formula shown above. Actual quantities vary with site conditions, layout, offcuts and installer practice. Verify with your supplier or contractor before ordering, and see our methodology.
How it works
- 1Add up the total wall length (perimeter) and ceiling height.
- 2Subtract standard 20 sq ft per door and 15 sq ft per window.
- 3Multiply by number of coats and divide by 350 sq ft coverage per gallon.
Formula
Worked example
A 12×14 room, 8 ft tall = 52 × 8 = 416 sq ft. Minus 1 door + 2 windows = 366 sq ft. Two coats ÷ 350 ≈ 2.1 gal.
Frequently asked questions
How much does a gallon cover?
Roughly 350 sq ft on primed drywall.
Do I need primer?
Yes on new drywall or drastic color changes.
How do I use the Paint Calculator?
Enter Room perimeter (ft), Wall height (ft), Doors and Windows. The paint calculator instantly returns Paintable wall area, Gallons required and Quart cans (if <1 gal), along with the formula and every calculation step so you can verify the result.
How much paint do I need?
It depends on your measurements, so run the paint numbers above rather than using a rule of thumb. The calculator applies the standard trade formula plus a stated waste allowance, which is what stops you from coming up short mid-job.
What does the Paint Calculator include in its result?
It reports Paintable wall area, Gallons required and Quart cans (if <1 gal). The underlying formula is Gallons = (Wall Area − Openings) × Coats ÷ 350 sq ft per gallon.
Is the Paint Calculator free, and does it work on mobile?
Yes — it's free, needs no account, and runs in the browser on phone, tablet and desktop. Nothing is installed and your saved paint estimates stay on your own device.
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