Paint Calculator
Calculate how many gallons of paint you need. Enter room dimensions, number of windows and doors, and coats.
Room Dimensions
Gallons Needed
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Estimated Cost
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Wall Area
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Ceiling Area
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Deductions
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Total Paintable
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Adds your paint takeoff into the Construction Estimate Builder.
Saved Estimates
Frequently Asked Questions
How many square feet does a gallon of paint cover?
One gallon of paint typically covers 350-400 square feet on a smooth, previously painted surface. Rough or porous surfaces like new drywall, textured walls, or bare wood may only get 200-300 sq ft per gallon. This calculator defaults to 350 sq ft/gallon, which is a safe average for most interior walls.
Do I really need two coats of paint?
Yes, in most cases. Two coats provide more uniform coverage, richer color, and better durability. One coat is sometimes acceptable when painting a similar color over an existing painted surface with a high-quality paint-and-primer-in-one. When changing from a dark to a light color, you may need a tinted primer plus two topcoats (essentially 3 coats).
How do I calculate paint for a room with vaulted ceilings?
For vaulted or cathedral ceilings, use the average ceiling height. Measure the lowest point and the peak, add them together, and divide by 2. For example, if your wall goes from 8 ft to 14 ft, use 11 ft as your ceiling height. This gives a close enough estimate for the additional wall area created by the slope.
Worked Example: Painting a Master Bedroom
Room: 14 ft x 12 ft, 8 ft ceilings, 1 door, 2 windows, 2 coats of paint
Step 1 - Wall Area: Perimeter = 2 x (14 + 12) = 52 ft. Wall area = 52 x 8 = 416 sq ft.
Step 2 - Deductions: 1 door (21 sq ft) + 2 windows (30 sq ft) = 51 sq ft.
Step 3 - Net paintable area: 416 - 51 = 365 sq ft per coat. With 2 coats: 730 sq ft total.
Step 4 - Gallons needed: 730 / 350 = 2.09 gallons. Round up to 3 gallons (paint is sold in gallons).
Step 5 - Cost: At $35/gallon, budget $105 for paint. Add $20-$40 for tape, drop cloths, and rollers.
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