How Much Paint for a 12×20 Room?
A 12×20 foot room has 512 sq ft of wall area. Subtract 1 door and 2 windows and you get 462 sq ft to paint — that's 1.4 gallons for 1 coat or 2.7 gallons for 2 coats of wall paint.
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Our editorial team researches and fact-checks material calculations with input from licensed contractors, landscape designers, and certified tradespeople across the US.
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Assumptions: 8 ft ceiling · 1 door (20 sq ft) · 2 windows (15 sq ft each) · 350 sq ft per gallon
Answer at a glance — 12×20 ft room
| What you're painting | Gallons needed |
|---|---|
| 1 coat, walls only | 1.4 gal |
| 2 coats, walls only | 2.7 gal |
| 1 coat, walls + ceiling | 2.1 gal |
| 2 coats, walls + ceiling | 4.1 gal |
How we calculated it
- Wall area = 2 × (12 + 20) × 8 ft = 512 sq ft
- Deductions = 1 door (20 sq ft) + 2 windows (30 sq ft) = 50 sq ft
- Net wall area = 512 − 50 = 462 sq ft
- Gallons per coat = 462 ÷ 350 = 1.4 gal
- Two coats = 2.7 gal
Ceiling: 12 × 20 = 240 sq ft → 0.7 gal per coat
Adjust for your room
- More or larger windows — each 15 sq ft window saves ~0.04 gallons per coat
- 9 ft ceilings — adds 64 sq ft more wall area (0.2 gal per coat extra)
- No door — add back 20 sq ft per missing door
- Dark color over light — may need a 3rd coat; buy extra accordingly
The Paint Calculator lets you enter your exact window count, ceiling height, and number of coats.
Paint buying tips
- Buy all cans in one trip — batch numbers affect color consistency
- Keep a quart of the same color for future touch-ups
- Use a separate primer coat if painting over dark colors or new drywall
Frequently Asked Questions
How many gallons of paint for a 12x20 room?
A 12×20 ft room has 512 sq ft of wall area. Subtract 1 door and 2 windows (50 sq ft) = 462 sq ft. That's 1.4 gallons for 1 coat or 2.7 gallons for 2 coats.
Do I need to paint the ceiling in a 12x20 room?
The ceiling in a 12×20 room is 240 sq ft — 0.7 gallons per coat of ceiling paint. Ceiling paint is typically white and sold separately from wall paint.
How long will it take to paint a 12x20 room?
Most DIYers can paint a 12×20 room in 4–8 hours for 2 coats including prep, drying time, and cleanup. Professionals cost $200–$500 for a room this size.
What paint sheen for a 12x20 room?
Bedrooms: eggshell or satin. Living rooms: eggshell. Bathrooms and kitchens: satin or semi-gloss. Trim and doors: semi-gloss or gloss.
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