How do I measure a room for paint?

Add wall lengths for perimeter, multiply by ceiling height, subtract doors and windows. Our single-room preset starts with a 120 ft perimeter × 4 ft height example.

How many gallons of paint for a room?

Paintable wall area = perimeter × height minus doors (~21 ft² each) and windows (~15 ft² each). Gallons = area × coats ÷ coverage (default 350 ft²/gal), rounded up.

How many coats should I plan for?

Two coats is standard for walls. One coat may suffice over similar color; new color or bare drywall often needs two. Adjust the coats field in the calculator.

Paint Calculator for One Room

Focused on one room? Start with perimeter and wall height. Default example: 120 ft perimeter × 4 ft height — adjust to match your space.

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Formula shown
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Rooms

Room 1

Perimeter (ft)

Wall height (ft)

Doors

Windows

Ceiling area (ft², optional)

Coats (Coverage)

Coverage (ft²/gal)

Price per gallon ($, optional)

1 coat at 250 ft²/gal on bare or patched walls

Adds 20% waste for overspray

Result

3 gallons

480 ft² paintable · 2 coats · 350 ft²/gal

Per room

Room 1: 480 ft² → 3 gal

480 ft² × 2 ÷ 350 = 3 gallons

350 ft²/gal coverage assumes mid-range interior latex with two coats — verify on your paint can label. Full methodology

Plan the rest of your project

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Focused on one room? Start with perimeter and wall height. Default example: 120 ft perimeter × 4 ft height — adjust to match your space.

Frequently asked questions

How do I measure a room for paint?: Add wall lengths for perimeter, multiply by ceiling height, subtract doors and windows. Our single-room preset starts with a 120 ft perimeter × 4 ft height example.
How many gallons of paint for a room?: Paintable wall area = perimeter × height minus doors (~21 ft² each) and windows (~15 ft² each). Gallons = area × coats ÷ coverage (default 350 ft²/gal), rounded up.
How many coats should I plan for?: Two coats is standard for walls. One coat may suffice over similar color; new color or bare drywall often needs two. Adjust the coats field in the calculator.

Frequently asked questions

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