Paint Coverage Calculator
Estimate gallons and cans for any room with doors, windows, coats, texture, and optional ceiling paint.
Walls
Openings
Each standard door counts as 20 sq ft.
Paint specs
Gallons (with waste)
2.29
Cans to buy
3
Estimated cost
$120
Buy 3 x 1-gallon cans
About 9.2 quarts if you buy quart cans instead. Includes 10% waste.
Area breakdown
- Total wall area
- 432 sq ft
- Openings deducted
- 68 sq ft
- Net paintable area
- 364 sq ft
- After texture
- 364 sq ft
- After coats
- 728 sq ft
Wall-by-wall breakdown
| Wall | Area (sq ft) |
|---|---|
| Wall 1 | 108 |
| Wall 2 | 108 |
| Wall 3 | 108 |
| Wall 4 | 108 |
Paint amounts are estimates. Check the label on your can for coverage on your surface before you buy.
How this tool works
List each wall width and height, subtract doors and windows, then pick coats and surface texture. The calculator adds 10% waste and rounds up to whole one-gallon cans.
Worked example
A 12 by 12 ft room with 9 ft walls (four walls at 12 x 9 ft), one door, two medium windows, and two smooth coats at 350 sq ft per gallon needs about three one-gallon cans with waste included.
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Frequently asked questions
What is standard paint coverage?
Most latex interior paints cover 350 to 400 square feet per gallon on smooth, previously painted walls. Textured or porous surfaces such as bare drywall, masonry, or heavily orange-peeled walls absorb more paint and typically yield 250 to 300 square feet per gallon. Always check the coverage rate printed on the specific can you plan to use.
Should I buy extra paint?
Yes. Order 10 to 15 percent more than the bare square footage calculation suggests. Paint is manufactured in batches, and a can purchased months later may have a slightly different tint that is noticeable on touch-ups. Store any sealed leftover cans in a temperature-controlled space away from freezing temperatures to keep the paint usable.
How many coats do I need?
Two finish coats are the standard for most repaint jobs over a similar color. Switching from a dark wall to a much lighter color may require three coats to achieve full hide. Bare or patched drywall typically needs a coat of primer first before any finish paint so the topcoats cover evenly and the sheen stays consistent.
Does ceiling paint count the same way?
Turn on the ceiling toggle to add your ceiling square footage and choose a coat count for that surface separately. Flat ceilings often use the same formula as walls. Many painters choose a ceiling-specific flat paint at a lower sheen level to minimize light reflection and hide surface imperfections that would show under a semi-gloss or eggshell finish.