How Much Paint Do I Need? Interior Room Paint Coverage & Gallon Guide

Buying too little paint causes inconvenient extra trips to the hardware store, while buying too much wastes money. Learning the standard paint coverage formula helps you purchase exact quantities.

Standard Paint Coverage Rule

As a rule of thumb, 1 gallon of quality interior paint covers approximately 350 square feet of smooth wall surface with 1 coat.

Square Footage Formula for Rooms

1. Wall Area: 2 × (Length + Width) × Height
2. Door Deduction: Subtract 21 sq ft per standard door
3. Window Deduction: Subtract 15 sq ft per standard window
4. Coats Required: Multiply paintable area by 2 for standard double-coat application

Estimate gallons and quart combinations instantly:

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