Paint Calculator
Gallons of paint for a wall area or a room size in feet, less doors and windows, ceiling optional, by texture, coats and waste, with gallons to buy and cost. How it works
Use the Paint Calculator
About the Paint Calculator
A 12 × 14 ft room with 8 ft walls has 416 sq ft of wall: 2 × (12 + 14) × 8. Two coats on smooth walls at 400 sq ft per gallon take 2.1 gallons, or 2.3 gallons with the default 10% waste. One door and two windows bring it down to 365 sq ft and 2.1 gallons. The paint calculator takes doors and windows off the wall area, works out area × coats ÷ coverage per gallon, adds the waste and rounds up to the next 0.1 gallon. Enter the room’s length, width and height instead of the wall area, and tick Paint the ceiling too to add it. The Buy line rounds up to whole gallons, and a price per gallon gives the cost.
Gallons for two coats by wall area and texture
| Wall area | Smooth (400 sq ft/gal) | Light texture (350) | Medium texture (300) | Heavy texture (200) |
|---|---|---|---|---|
| 100 sq ft | 0.6 | 0.7 | 0.8 | 1.1 |
| 200 sq ft | 1.1 | 1.3 | 1.5 | 2.2 |
| 400 sq ft | 2.2 | 2.6 | 3 | 4.4 |
| 600 sq ft | 3.3 | 3.8 | 4.4 | 6.6 |
| 1,000 sq ft | 5.5 | 6.3 | 7.4 | 11 |
Gallons with the default 10% waste, rounded up to the next 0.1 gallon.
Frequently asked questions
- How much paint do I need for a 10 × 12 room?
- With 8 ft walls the wall area is 2 × (10 + 12) × 8 = 352 sq ft, and two coats on smooth walls come to 2 gallons with 10% waste. Enter one door and one window and the paintable area drops to 316 sq ft, 1.8 gallons.
- Do I subtract doors and windows?
- Yes, and the calculator does it for you: type the full wall area, then the number of doors and windows. Each door takes off 21 sq ft (3 × 7 ft) and each window 15 sq ft (3 × 5 ft) by default, and both sizes can be changed. In the 12 × 14 ft room, one door and two windows leave 365 sq ft, which is 2.1 gallons for two smooth coats instead of 2.3, or 2.7 gallons on the default medium texture.
- How many square feet does a gallon of paint cover?
- The calculator assumes 400 sq ft per coat on a smooth wall, 350 on light texture, 300 on medium and 200 on heavy texture such as stucco or popcorn. The can states the maker’s own figure; the coverage cannot be typed in, so pick the texture whose rate is closest to it.
- How many gallons of paint should I buy?
- The Buy line rounds the estimate up to whole gallons, and a price per gallon is charged on those: 500 sq ft of medium texture with two coats and 10% waste is 3.7 gallons, so buy 4, which at $35 a gallon is $140.00. Saved estimates add their gallons first and round the total up once.
- Does the estimate include the ceiling?
- Yes, when you measure by Room size and tick Paint the ceiling too: length × width is added after the doors and windows come off the walls. A 14 × 12 ft room with 8 ft walls, one door and two windows has 365 sq ft of wall, and the ceiling brings it to 533 sq ft, 4 gallons at the default medium texture. On its own, that ceiling is 168 sq ft, 1 gallon for two smooth coats with 10% waste.
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