Paint Calculator
Estimate gallons of paint for any room — doors and windows subtracted.
Use this free room paint calculator to estimate how many gallons you need from the room length, width, ceiling height, doors, windows, and number of coats. It subtracts standard door and window areas, applies 350 square feet of coverage per gallon, and shows the amount to buy.
Gallons
1.81
Buy the next whole gallon
Paintable area
316 ft²
Total wall area
352 ft²
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Recommended tools & materials
Handy picks for this project on Amazon.
Paint Roller Kit
Roller, tray and covers in one set
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Angled Sash Brush
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Painter's Tape
Clean lines, no residue
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Canvas Drop Cloth
Protect floors and furniture
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How does the paint calculator work?
Wall area is the room perimeter × ceiling height. Subtract roughly 21 ft² per door and 15 ft² per average window, then multiply by the number of coats and divide by 350 ft²/gallon.
Formula: gallons = ((2(L+W) × H − doors×21 − windows×15) × coats) ÷ 350
What do people use the paint calculator for?
Paint for a Bedroom
Estimate gallons of paint for any bedroom.
Paint for a Living Room
Estimate gallons of paint for a living room.
Paint for a House Exterior
Estimate gallons of exterior paint for siding and trim.
Paint for a Ceiling
Estimate gallons of paint for any ceiling.
Paint for Cabinets
Estimate quarts and gallons for a kitchen cabinet repaint.
What else do people ask about this calculator?
How much paint do I need for a 12×12 room?
A 12×12 room with 8 ft ceilings, 1 door and 1 window needs about 2 gallons for two coats.
How much does a gallon of paint cover?
About 350 ft² per gallon on smooth interior walls. Textured or porous surfaces reduce coverage to 250–300 ft².
Which related calculators should I use next?
Where can I learn more about these materials?
Weights, coverage, types and buying tips for the materials this calculator estimates.
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Complete Your Painting Setup
Protect your space and achieve cleaner results with these practical painting supplies.
ScotchBlue Painter's Tape
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Trimaco Canvas Drop Cloth
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Shur-Line Paint Edger Pro
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