How much paint do I need for a 12×12 room?
A 12×12 bedroom with standard 8-foot ceilings, one door, and two windows needs about 2 gallons for two coats. Here’s exactly where that number comes from — and how to adjust it for your room.
Your walls come to about 334 sq. ft. after doors and windows. At 2 coats and 350 sq. ft. per gallon, that’s 1.9 gallons — buy 2 to be covered.
Adjust These Numbers for Your ProjectThe math, step by step
- Wall perimeter: 2 × (12 + 12) = 48 ft
- Gross wall area: 48 × 8 = 384 sq. ft.
- Openings: (1 × 20) + (2 × 15) = 50 sq. ft.
- Paintable area: 384 − 50 = 334 sq. ft.
- With 2 coats: 334 × 2 = 668 sq. ft.
- Gallons: 668 ÷ 350 = 1.91 → buy 2
- Each door counts as 20 sq. ft. and each window as 15 sq. ft.
- Coverage varies by surface, product, application method, and manufacturer.
- Walls only — ceilings and trim need their own paint.
The two-coat assumption matters more than anything else on this page. One coat only works when you’re repainting a similar color in good condition; a color change (especially covering dark walls) or fresh drywall almost always needs two, and going from dark to light sometimes needs a dedicated primer coat on top of that. If you’re changing color dramatically, budget the primer separately — it covers about the same area per gallon.
Ceiling height is the silent multiplier. The same 12×12 room with 9-foot ceilings adds about 48 sq. ft. of wall — enough to tip you from “2 gallons is plenty” to “the second gallon runs out on the last wall.” Measure your actual wall height before trusting any rule of thumb, including ours.
One practical tip: buy both gallons at once and have the store shake them, then box them (pour both into one container and mix) if you’re picky about color consistency. Tinted paint can vary slightly can-to-can, and a mid-wall color shift is more visible than you’d think.
Frequently asked questions
Is one gallon enough for a 12×12 room?
Only for one coat (about 334 sq. ft. of wall). For two coats you need roughly 1.9 gallons, so buy 2. One gallon works if you’re refreshing the same color on well-conditioned walls.
Does this include the ceiling?
No — walls only. A 12×12 ceiling is another 144 sq. ft., which is most of a gallon’s worth for one coat. Ceilings usually use flat ceiling paint, so buy it separately.
What if my room has more windows or a second door?
Each window subtracts about 15 sq. ft. and each door about 20 sq. ft. A couple of extra openings rarely change the buy recommendation — the rounding usually absorbs it.