How Much Paint for a 20×20 Room?
A 20×20 foot room has 640 sq ft of wall area. Subtract 1 door and 2 windows and you get 590 sq ft to paint — that's 1.7 gallons for 1 coat or 3.4 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 — 20×20 ft room
| What you're painting | Gallons needed |
|---|---|
| 1 coat, walls only | 1.7 gal |
| 2 coats, walls only | 3.4 gal |
| 1 coat, walls + ceiling | 2.9 gal |
| 2 coats, walls + ceiling | 5.7 gal |
How we calculated it
- Wall area = 2 × (20 + 20) × 8 ft = 640 sq ft
- Deductions = 1 door (20 sq ft) + 2 windows (30 sq ft) = 50 sq ft
- Net wall area = 640 − 50 = 590 sq ft
- Gallons per coat = 590 ÷ 350 = 1.7 gal
- Two coats = 3.4 gal
Ceiling: 20 × 20 = 400 sq ft → 1.2 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 80 sq ft more wall area (0.3 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 20x20 room?
A 20×20 ft room has 640 sq ft of wall area. Subtract 1 door and 2 windows (50 sq ft) = 590 sq ft. That's 1.7 gallons for 1 coat or 3.4 gallons for 2 coats.
Do I need to paint the ceiling in a 20x20 room?
The ceiling in a 20×20 room is 400 sq ft — 1.2 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 20x20 room?
Most DIYers can paint a 20×20 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 20x20 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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