How much area does a gallon of paint cover?

One gallon of interior latex paint covers approximately 350-400 square feet (32.5-37 square meters) per coat on smooth surfaces. Textured walls, bare drywall, or porous surfaces may reduce coverage to 200-300 square feet per gallon.

How do I calculate the square footage of my walls?

Measure each wall's width and height in feet, then multiply them together. Add all walls together. Subtract window and door areas (about 15-20 sq ft per window, 20 sq ft per door). Formula: Total wall area = perimeter × height - openings.

How many coats of paint do I need?

Most paint jobs require 2 coats for even coverage. Painting over a dark color with a light one may require 3 coats or a tinted primer first. Going from light to dark typically needs 2 coats. New drywall needs primer plus 2 coats.

How to Calculate Paint Coverage

Paint Coverage Formula

Gallons needed = (Total wall area in sq ft × Number of coats) ÷ 350

For a room, calculate total wall area: Perimeter (ft) × Height (ft) − Windows and Doors

Quick Room Estimation

Room Size	Perimeter	Wall Area (8' ceiling)	Gallons (2 coats)
10×10 ft	40 ft	~290 sq ft	1.5-2 gal
12×12 ft	48 ft	~350 sq ft	2 gal
14×14 ft	56 ft	~410 sq ft	2.5 gal
16×16 ft	64 ft	~475 sq ft	3 gal
20×20 ft	80 ft	~600 sq ft	3.5-4 gal

Coverage by Paint Type

Paint Type	Coverage (sq ft/gal)	Coverage (m²/L)
Interior latex	350-400	8.6-9.8
Interior oil-based	350-400	8.6-9.8
Exterior latex	250-350	6.1-8.6
Primer	200-300	4.9-7.4
Stain (deck/fence)	150-250	3.7-6.1

Step-by-Step Example

A 14×12 ft bedroom with 8-foot ceilings

Perimeter: (14 + 12) × 2 = 52 feet
Gross wall area: 52 × 8 = 416 sq ft
Subtract: 2 windows (30 sq ft) + 1 door (20 sq ft) = 50 sq ft
Net area: 416 − 50 = 366 sq ft
For 2 coats: 366 × 2 = 732 sq ft of coverage needed
Gallons: 732 ÷ 350 = 2.1 gallons → buy 3 gallons

Calculate areas with our area converter.