How much paint for a 10x12 room?

A 10 x 12 ft room with 8 ft walls has 352 sq ft of wall. After subtracting a door and two windows, two coats is about 604 sq ft, which is roughly 1.73 gallons at 350 sq ft per gallon. Buy 2 gallons.

Is one gallon of paint enough for a room?

Sometimes. A small room with one coat may need less than a gallon, but two coats is the usual standard, which often pushes a normal bedroom past one gallon. Calculate by area rather than guessing.

Does a second coat use the same amount of paint?

Roughly, yes. Each coat covers approximately the same area, so two coats needs about twice the paint of one coat.

How Much Paint Do I Need?

A step-by-step way to estimate paint for a room, including how doors and windows change the wall area and why coverage matters.

Last updated: September 25, 2026

Time to estimate: About 5 minutes
Difficulty: Easy
You need: Tape measure, calculator

To estimate how much paint you need, calculate the total paintable wall area, subtract the area of doors and windows, multiply by the number of coats, and divide by the paint's coverage per gallon. Then round up, because paint is sold in whole containers.

Step by step

Measure the length and width of the room in feet, plus the wall height from floor to ceiling.
Find the wall area: 2 × (length + width) × height. For a 12 x 10 ft room with 8 ft walls, that is 2 × 22 × 8 = 352 sq ft.
Subtract openings. A typical door removes about 20 sq ft and a typical window about 15 sq ft.
Add the ceiling if you plan to paint it: length × width.
Multiply the paintable area by the number of coats.
Divide by the coverage printed on the can, commonly 350 to 400 sq ft per gallon per coat.
Round up to the nearest whole gallon.

Worked example

A 12 x 10 ft room with 8 ft walls, one door, two windows, two coats, and no ceiling painted:

wall area      = 2 × (12 + 10) × 8 = 352 sq ft
openings       = 20 + (2 × 15)    = 50 sq ft
paintable area = 352 − 50         = 302 sq ft
two coats      = 302 × 2          = 604 sq ft
gallons        = 604 ÷ 350        = 1.73
buy            = 2 gallons

Run your own numbers with the paint calculator.

What changes the estimate

Surface texture. Stucco, brick, and rough wood absorb more paint and cover less area per gallon.
Color change. Going from dark to light may need an extra coat or a tinted primer.
Coverage claims. Some paints advertise higher coverage, but real results depend on the surface and application.

Buy in the same batch

For more than one gallon of the same color, mix the containers together or confirm they share a batch code. Small differences between batches can show after the paint dries.

When to call a professional

Consider a professional for very high or hard-to-reach walls, exterior surfaces above the first story, or homes built before 1978 where lead-based paint may be present. Disturbing lead paint without the right precautions is a health risk.

Sources and assumptions

Coverage figures come from the ranges printed on interior paint labels. The 20 sq ft door and 15 sq ft window values are common estimating conventions, not exact measurements.

Frequently asked questions

How much paint for a 10x12 room?: A 10 x 12 ft room with 8 ft walls has 352 sq ft of wall. After subtracting a door and two windows, two coats is about 604 sq ft, which is roughly 1.73 gallons at 350 sq ft per gallon. Buy 2 gallons.
Is one gallon of paint enough for a room?: Sometimes. A small room with one coat may need less than a gallon, but two coats is the usual standard, which often pushes a normal bedroom past one gallon. Calculate by area rather than guessing.
Does a second coat use the same amount of paint?: Roughly, yes. Each coat covers approximately the same area, so two coats needs about twice the paint of one coat.

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