Free planning tool
Paint quantity and leftover calculator.
Compare what you'd buy for a painting project. Put in the room, the doors and windows, the number of coats, the coverage printed on the can and the container you'd buy, and see the paint you need, the containers to purchase, what goes unused and what it costs.
What to buy
3 gallons, about $144.
- Area to paint
- 396 sq ft
- Paint needed (2 coats)
- 2.26 gal
- Containers to buy
- 3
- Unused capacity
- 0.74 gal
- Paint cost
- $144
Paint only. Primer, patching, tape and the labor go on Brad's written estimate after a visit.
How the math works
Four lines. The calculator measures the walls, takes out the openings, multiplies by coats and divides by the can's coverage.
- Area to paint = 2 × (length + width) × ceiling height − 21 sq ft per door − 15 sq ft per window, plus length × width if the ceiling is included
- Paint needed (gallons) = area to paint × coats ÷ coverage per gallon
- Containers = paint needed ÷ container size, rounded up; unused = containers × size − paint needed
- Cost = containers × price per container
The sample numbers
The tool opens with a 12 by 14 bedroom with 9-foot ceilings: 468 square feet of wall, less two doors and two windows, 396 square feet to paint.
Two coats at 350 square feet per gallon is 2.26 gallons, which rounds up to 3 gallons, with about three quarters of a gallon left unused; at $48 a can, $144.
- Sample room 12 by 14 by 9 ft, 2 doors, 2 windows: 396 sq ft
- Two coats at 350 sq ft per gallon: 2.26 gal, 3 cans, $144
- With the ceiling: 564 sq ft, 3.22 gal, 4 cans
- Coverage from the product label, never assumed
The details
Switch the container to a 5-gallon bucket and the same job needs one bucket with 2.74 gallons unused; the unit price is lower but the leftover is bigger. Tick the ceiling and the area climbs to 564 square feet, 3.22 gallons, four cans. That comparison, size against leftover, is what the tool is for.
Coats and coverage
Two coats is the normal job.
One coat covers a touch-up in the same color; three is for a deep color over a light one, or any color over a dark one, unless the first coat is a tinted primer. Coverage on the label is for a smooth, previously painted wall; fresh drywall, patched walls and knockdown texture drink more, so use the low end of the label's range.
- Same color refresh: 1 coat
- Color change on painted walls: 2 coats
- Dark over light or light over dark: 3 coats, or primer plus 2
- New drywall or texture: use the label's low coverage figure
The details
Buy the last can in the same batch as the first. Tint varies a hair between mixes, and the wall where two cans meet shows it.
More free tools.
Questions about this tool
Something else on your mind? Call or text (954) 242-5924.
Does the calculator include primer, patching or labor?
No. It counts finish paint only. Primer, patching, tape, drop cloths and the labor go on Brad's written estimate.
Why 21 square feet per door and 15 per window?
A standard 3 by 7 door is 21 square feet and a common 3 by 5 window is 15. If yours are different, add or subtract the difference in the length field; the tool is a planning estimate, not a takeoff.
Does it send my measurements anywhere?
No. The math runs in your browser and nothing you type is stored or sent. Our analytics only records that the tool was used.
Get a free estimate.
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