How Much Paint for a 12x20 Room?
Paint needed
2.5 gallons
A 12 by 20 room with eight foot walls, two doors, three windows, 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 walls64 ft
- Wall height8 ft
- Doors2
- Windows3
- Coats2
- Coverage per gallon350 sq ft
Paint needed2.5 gallons
| Gross wall area | 512 sq ft |
|---|---|
| Less doors and windows | -87 sq ft |
| Net wall area | 425 sq ft |
| Area over 2 coats | 850 sq ft |
| Gallons, exact | 2.43 |
| Buy | 3 gallonsor 1 five gallon pail |
The material list this produces
| Paint, gallons | 3 |
|---|---|
| Primer, gallons (if bare or color change) | 2 |
| Painter's tape, rolls | 2 |
Coats compared
Same room, one coat to three.
| Coats | Paint needed |
|---|---|
| 1 coat | 1.25 gallons |
| 2 coats | 2.5 gallons |
| 3 coats | 3.75 gallons |
What else matters here
Sixty four feet of perimeter, two doors and three windows: 425 square feet net and 2.43 gallons over two coats.
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 a 12x20 room?
About 2.43 gallons for two coats on eight foot walls with two doors and three windows, so buy three gallons.
The paint calculator takes any dimensions you like and hands back the same list.