Paint Calculator
Calculate the exact amount of paint you need for any room. Enter room dimensions, number of doors and windows, and get results for one-coat and two-coat coverage.
Input Values
Results
How to Use This Calculator
How to Use the Paint Calculator
- **Measure the Room Length** — Measure the longest wall of the room in feet.
- **Measure the Room Width** — Measure the wall perpendicular to the length in feet.
- **Enter the Wall Height** — Standard wall height is 8 feet. Adjust if your ceilings are taller or shorter.
- **Count Doors and Windows** — Enter the number of standard doors and windows. The calculator subtracts 21 sq ft per door and 15 sq ft per window.
- **Review Results** — You will see the paintable area and the number of gallons needed for both one coat and two coats.
For Best Results - Measure each wall individually if the room is not a standard rectangle. - Exclude areas that will not be painted, such as built-in bookshelves or stone accents. - Use a primer if painting over dark colors or bare surfaces — primer is calculated separately.
Tips & Best Practices
- ✓Use painter's tape to protect trim, ceiling edges, and window frames for crisp, clean lines.
- ✓Stir paint thoroughly before use and periodically during application — never shake a can of latex paint.
- ✓Roll in a "W" pattern on the wall, then fill in evenly to avoid streaks and roller marks.
- ✓Allow 2–4 hours of drying time between coats for latex paint and 24 hours for oil-based paint.
- ✓Buy all your paint at once to ensure color consistency — different batches may have slight color variations.
Frequently Asked Questions
How much paint do I need for a 12x12 room?
A 12×12 room with 8 ft ceilings, 1 door, and 2 windows has about 333 sq ft of paintable area. You will need approximately 1 gallon for one coat or 2 gallons for two coats.
How many square feet does a gallon of paint cover?
One gallon of paint typically covers about 350–400 square feet with one coat. Coverage varies by paint quality, surface texture, and application method. Rough or porous surfaces will use more paint.
Do I need to apply two coats of paint?
Two coats are recommended in most situations for a uniform, durable finish. A second coat is especially important when changing from a dark to a light color, painting over bare drywall, or using a lighter paint shade.
Should I buy extra paint?
Yes, buy about 10–15% more than calculated. Extra paint is useful for touch-ups, covering missed spots, and future maintenance. Keep leftover paint stored properly for at least a few years.
How do I calculate paint for a ceiling?
Multiply the room length by the room width to get the ceiling area in square feet. Divide by 350 to get gallons needed per coat. This calculator focuses on walls — add ceiling calculations separately.