Paint Calculator
Room dimensions or individual walls, unlimited doors and windows, optional ceiling, coats, waste, and per-gallon pricing.
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Paint & Walls
Estimating paint comes down to one idea: paintable area times coats, divided by coverage. The tools and tips below handle the tedious parts — openings, accent walls, ceilings, and waste.
Start with the calculator
What you can calculate
- Gallons or litres of wall paint for a whole room, including two-coat jobs.
- Ceiling paint when you include the ceiling in room mode.
- Partial jobs — an accent wall or a half-painted room — using individual wall mode.
- Estimated cost from your own price per gallon or litre.
Measuring tips for walls
- Measure wall length at floor level and height from floor to ceiling — baseboards and crown moulding do not change the paintable area much, but skim coats and texture do affect coverage.
- Count each door and window once and use the quantity field for repeats, instead of adding the same opening several times.
- For L-shaped or truncated rooms, switch to individual-wall mode and enter each wall's width and height — the room-perimeter formula assumes four walls.
- Very dark wall colors over light paint often need an extra coat; raise the coat count rather than the waste percentage for that.
Guides for paint projects
- How to Calculate How Much Paint You Need — the full manual method behind the calculator.
- How Much Extra Material Should You Buy? — choosing a sensible waste percentage.
Related calculators
- Flooring Calculator — painting the room? You may be flooring it next.
- Drywall Calculator — hanging new board before you paint?
- Concrete Calculator — for exterior paint-project pads and walkways.