Paint Calculator
Calculate how many gallons of paint you need for a room. Accounts for walls, ceiling, doors, and windows for accurate estimates.
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Wall Paint (gallons)
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Ceiling Paint (gallons) —
Total Gallons —
Net Paintable Area —
Extended More scenarios, charts & detailed breakdown ▾
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Wall Gallons
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Ceiling Gallons —
Total Gallons —
Wall Area —
Professional Full parameters & maximum detail ▾
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sqft/gal
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Paint Quantities
Net Wall Area —
Wall Gallons —
Ceiling Gallons —
Total Gallons —
Cost Estimate
Paint Cost —
Labor Hours —
Labor Cost —
Total Project Cost —
How to Use This Calculator
- Enter the room length, width, and ceiling height in feet.
- Enter the number of doors and windows to subtract.
- Select whether to include the ceiling and number of coats.
- Results show gallons needed for walls and ceiling separately.
Formula
Wall area = 2 × (L + W) × H − doors × 20 − windows × 15
Gallons = ceil(Wall area × coats ÷ 350)
Example
Example: 12 × 14 ft room, 9 ft ceiling, 1 door, 2 windows, 2 coats → Wall area 450 sq ft → 3 gallons.
Frequently Asked Questions
- One gallon of paint typically covers 350–400 square feet. This calculator uses 350 sq ft per gallon as a conservative estimate.
- Yes — set the number of coats to 2 for a solid finish, especially when changing colors. The calculator multiplies the gallons needed by the number of coats.
- Yes — enter the number of standard doors (20 sq ft each) and windows (15 sq ft each) and the calculator deducts them from the paintable area.
- Yes. The calculator optionally includes the ceiling area if you check the "Include ceiling" field. Ceiling paint is typically bought separately.
- Add up the areas of each wall manually and enter the total wall area, leaving the room dimensions as a guide.