Interior Paint Calculator
Walls · Ceiling · Doors · Windows · Cost
Each door ≈ 21 sqft
Each window ≈ 15 sqft
Budget $25 | Premium $65+
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Wall Area
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Wall Gallons
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Ceiling Gallons
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Total Paint Cost
About This Calculator
The Paint Calculator takes the guesswork out of buying paint. Too little and you run out mid-job; too much wastes money. This calculator accounts for wall area, deductions for doors and windows, number of coats, and ceiling area if needed.
Standard coverage: one gallon covers approximately 350–400 sqft with one coat. Most rooms need two coats for even, professional-looking coverage. Dark colors over light surfaces may require a third coat.
Pro tips: buy all paint at once from the same batch for color consistency; keep leftover paint for touch-ups; choose the right sheen — flat for ceilings, eggshell or satin for walls, semi-gloss for trim and bathrooms.
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Frequently Asked Questions
How many gallons of paint do I need for a 12x12 room?▼
A 12×12 room with 8-ft ceilings has about 384 sqft of wall area. Subtract doors and windows (~70 sqft) = ~314 sqft net. At 2 coats with 350 sqft/gallon coverage, you need approximately 2 gallons for the walls. Add 1 gallon for the ceiling.
How much wall area does a gallon of paint cover?▼
Most paints cover 350–400 sqft per gallon with one coat. This is the manufacturer's estimate under ideal conditions. Real-world coverage is often closer to 300–350 sqft due to texture, absorption, and application method.
Is one coat of paint enough?▼
One coat is rarely enough for complete coverage. Two coats is standard. You may need three coats when: painting over dark colors, using saturated colors, covering stains, or using cheaper paint. A quality primer can reduce the coats needed.
What's the difference between paint sheens?▼
Flat/matte: best for ceilings and low-traffic walls (hides imperfections). Eggshell: popular for living areas — easy to clean. Satin: good for bedrooms and hallways. Semi-gloss: kitchens, bathrooms, trim — moisture resistant. Gloss: doors and trims.
How much does it cost to paint a room?▼
DIY: $50–$200 in materials for an average bedroom. Professional painter: $300–$800 per room (labor + materials). Whole-house professional painting ranges from $1,500 to $4,000+ depending on size and condition.
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