How Much Paint Do I Need for a Room? A Simple Guide
For most bedrooms, the answer is about 2 gallons of wall paint for two coats. Bigger rooms, higher ceilings and dark color changes need more. Here is how to work out your exact number, or use the paint calculator to do it in seconds.
The paint formula
wall area = perimeter × wall height − doors − windows
gallons = wall area × coats ÷ 350
The perimeter is the distance around the room: 2 × (length + width). A standard door is about 21 sq ft and a window about 15 sq ft. 350 sq ft per gallon is a cautious coverage figure for most interior paint; check your can.
Example: a 12 × 14 ft bedroom
- Perimeter: 2 × (12 + 14) = 52 ft
- Wall area: 52 × 8 ft high = 416 sq ft
- Subtract one door and two windows: 416 − 21 − 30 = 365 sq ft
- Two coats: 730 sq ft ÷ 350 = 2.1 gallons
That's 2 gallons plus a quart. In practice, if a quart costs more than half a gallon, buy 3 gallons and keep the rest for touch-ups.
Paint by room size (two coats, walls only)
| Room | Gallons |
|---|---|
| Small bathroom (5 × 8 ft) | about 1 |
| Small bedroom (10 × 10 ft) | about 1.5 |
| Average bedroom (12 × 12 ft) | about 2 |
| Living room (14 × 16 ft) | about 2.5 |
| Large room, 9 ft ceiling (16 × 20 ft) | about 3.5 |
What changes how much paint you need
- Color change: going from dark to light (or to a bright red or yellow) can need a third coat or a tinted primer.
- New drywall: prime first. Bare drywall soaks up paint and will make your topcoat look patchy.
- Texture: heavy texture and popcorn ceilings can use 20–30% more paint.
- Paint quality: better paints often cover in fewer coats, which can make them cheaper overall.
Don't forget the ceiling and trim
Ceiling area is simply length × width. A 12 × 14 ceiling is 168 sq ft: about 1 gallon for two coats. Trim and doors usually need only a quart or two of semi-gloss for an average room.