How Much Paint for an 8x12 Room?
Paint needed
1.75 gallons
An 8 by 12 room with eight foot walls, one door, one window, two coats.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Room perimeter, add all walls40 ft
- Wall height8 ft
- Doors1
- Windows1
- Coats2
- Coverage per gallon350 sq ft
Paint needed1.75 gallons
| Gross wall area | 320 sq ft |
|---|---|
| Less doors and windows | -36 sq ft |
| Net wall area | 284 sq ft |
| Area over 2 coats | 568 sq ft |
| Gallons, exact | 1.62 |
| Buy | 2 gallonsor 1 five gallon pail |
The material list this produces
| Paint, gallons | 2 |
|---|---|
| Primer, gallons (if bare or color change) | 1 |
| Painter's tape, rolls | 1 |
Coats compared
Coats is the input people get wrong, usually by hoping. Same room, one coat to three.
| Coats | Paint needed |
|---|---|
| 1 coat | 1 gallon |
| 2 coats | 1.75 gallons |
| 3 coats | 2.5 gallons |
What else matters here
Forty feet of perimeter, 284 square feet net, and 1.62 gallons over two coats. Two gallons buys it with a third of a gallon spare, which is the right amount to keep.
Keep the leftover in a sealed quart tin rather than in the gallon it came in. A gallon can with an inch of paint in it has most of a gallon of air above the paint, and that air skins the surface and rusts the rim until the tin is useless within a year.
Label it with the room, the sheen and the date. Paint that has been stored properly is good for several years and will still match, which turns every future scuff into a five minute job instead of a repainted wall.
What this calculator assumes
- A door is taken as 21 sq ft and a window as 15 sq ft. Deducting them matters on a small room and barely moves a big one.
- 350 sq ft per gallon is the usual figure on a smooth primed wall. Bare drywall, textured walls and deep color changes all drink more, so drop it to 300 if any of those apply.
- Ceilings and trim are not included. Run the ceiling as its own area.
Questions people ask
How much paint for an 8x12 room?
About 1.62 gallons for two coats on eight foot walls, so buy two gallons.
How should I store leftover paint?
Decant it into a smaller sealed tin so there is little air above it, label it with the room and the sheen, and keep it somewhere that does not freeze.
How long does leftover paint last?
Several years stored properly in a full, sealed container. In a part empty gallon can it usually skins over and is unusable within a year.
The paint calculator takes any dimensions you like and hands back the same list.