How much paint for a 12×12 room?
A 12 × 12 ft room with 8 ft ceilings needs about 2 gallons of paint for two coats on the walls. Add 1 more gallon if you're painting the ceiling. Here's the quick math, what changes with taller ceilings or darker colors, and what the whole job costs.
The math
For a 12 × 12 room with 8 ft walls:
- Wall area = 2 × (12 + 12) × 8 = 384 sq ft
- Minus openings ≈ 21 sq ft per door + 15 sq ft per window → about 348 sq ft with one of each
- Two coats = 348 × 2 = 696 sq ft ÷ 350 (coverage per gallon) = 1.99 → 2 gallons
Round up to 2 gallons and keep the leftover for touch-ups.
Paint by room size (walls, 2 coats)
| Room size (8 ft walls) | Gallons (2 coats) |
|---|---|
| 10 × 10 ft | 2 gallons |
| 10 × 12 ft | 2 gallons |
| 12 × 12 ft | 2 gallons |
| 12 × 14 ft | 3 gallons |
| 14 × 16 ft | 3 gallons |
Ceiling height changes the answer
The chart above assumes standard 8 ft walls. Taller rooms add wall area fast — same 12 × 12 footprint, one door and one window:
| Ceiling height | Wall area | 2 coats needs | Buy |
|---|---|---|---|
| 8 ft | ~348 sq ft | 1.99 gal | 2 gallons |
| 9 ft | ~396 sq ft | 2.26 gal | 3 gallons (or 2 gal + quarts) |
| 10 ft | ~444 sq ft | 2.54 gal | 3 gallons |
A quart covers about 87 sq ft, so when the math leaves you just barely over a round number, a gallon plus a quart of the same line can beat buying a whole extra gallon — but only if the store tints that color in quarts.
Don't forget the ceiling, trim, and primer
- Ceiling: 144 sq ft → 1 gallon of flat ceiling paint handles one coat with enough left for a light second pass.
- Trim: the room's baseboard (~48 linear ft), a door, and a window casing add up to roughly 50 sq ft of surface — 1 quart of semi-gloss is usually plenty.
- Primer: only needed over bare drywall, patches, stains, or a dramatic color change. A full prime coat on these walls takes 1–2 gallons (primer covers ~200–300 sq ft per gallon); spot-priming patches takes far less.
What it costs to paint a 12×12 room
Interior wall paint runs $25–$60 per gallon for the mid-range lines most people buy, so the two wall gallons cost $50–$120. Add a gallon of ceiling paint and a quart of trim paint ($35–$80) and, if you're starting from zero, $25–$50 of rollers, brushes, tape, and drop cloths. Realistic DIY total: $75–$250. A professional painter typically charges $300–$800 for a room this size — our guide to the cost of painting a house breaks down per-room and whole-home pricing.
Buying tips that save a trip (or a gallon)
- Buy it all at once. Gallons tinted in separate batches can differ slightly in shade — and always note the formula code from the can label in your phone for future touch-ups.
- Test with a sample quart first. A $5–$10 sample saves repainting a whole room in a color that looked different on the card.
- Dark colors need a third coat. Three coats ≈ 1,044 sq ft ≈ 3 gallons; a tinted primer under a big color change usually saves one coat of the pricier paint.
- Spraying uses more. Airless sprayers lay paint fast but overspray and hose losses add 20–30% to consumption — the roller math above doesn't apply.
- Keep a labeled quart of leftovers. Scuffs and nail holes are inevitable; matching paint later rarely is.
Different size or ceiling height?
The paint calculator handles any room — coats, doors, windows, the ceiling, and your paint price — in seconds.
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