PAINT
PAINT GALLONS
gal = ft² × coats ÷ 350
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RESULT
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FILL IN ABOVE
1 gallon ≈ 350 ft² on smooth surfaces, 250–300 on rough/textured. Always round up.
About this calculator
This paint calculator tells you how many gallons of paint you need for a room. One gallon covers about 350 square feet on smooth walls or 275 on rough/textured surfaces. Enter your room length, width, ceiling height, the number of coats you plan to apply, and whether the surface is smooth or rough — the calculator rounds up to the nearest whole gallon since paint is sold by the gallon.
Common questions
How much paint do I need for a 12×12 room?
A 12×12 room with 8 ft ceilings has about 384 ft² of wall area. At 350 ft²/gallon coverage with 2 coats, you need about 2.2 gallons — round up to 3. Add another gallon if you're also painting the ceiling.
Should I buy 1-gallon cans or a 5-gallon bucket?
Buy a 5-gallon bucket if you need 4+ gallons — it's typically 15–20% cheaper per gallon and ensures color consistency across the whole job. For smaller jobs, gallon cans are fine and easier to handle.
How many coats of paint do I really need?
Two coats is standard and what this calculator assumes. One coat may work if you're repainting the same color over a clean surface. Always do two for color changes, dark over light, or any flat → satin/semi-gloss transitions.