Home Improvement
Paint Quantity Calculator
Calculate the amount of paint needed for walls, ceilings, and trim.
Room Dimensions
Room Length
ft
Length of the room
Room Width
ft
Width of the room
Ceiling Height
ft
Height of the walls
Surface Details
Number of Doors
doors
Average door area: 20 sq ft per door
Number of Windows
windows
Average window area: 15 sq ft per window
Surface Type
Rough surfaces require more paint coverage
Paint Coverage
Coverage per Gallon
sq ft
Paint coverage in square feet per gallon
Number of Coats
coats
Recommended 2 coats for best coverage
Paint
0
Total Paint Needed
0 gal
gallons required
Wall Area
0 sq ft
Ceiling Area
0 sq ft
Total Paintable Area
0 sq ft
Liters Required
0 L
📊 Detailed Breakdown
| Category | Area | % of Total |
|---|
How the formula works
Wall Area = 2 × (Length + Width) × Height − (Doors × 20 + Windows × 15) | Ceiling Area = Length × Width
- Wall Area = 2 × (Length + Width) × Height − (Doors × 20 + Windows × 15)
- Ceiling Area = Length × Width
- Total Area = Wall Area + Ceiling Area (walls + ceiling)
- Paint Needed = Total Area × Coats / (Coverage × Surface Factor)
- Surface Factors = Smooth (1.0), Textured (1.2), Rough (1.4)
- Liters = Gallons × 3.78541
- Average door area: 20 sq ft, Average window area: 15 sq ft
- Always round up to the nearest gallon or liter