Paint Calculator
Estimate how much paint you need for a room, including wall area, doors and windows, number of coats, waste, containers to buy, and approximate paint cost.
✏️ Inputs
Choose your region, then enter your room and paint details.
🏠 Room size
🚪Doors and windows
🪣 Paint settings
Estimate disclaimer: This estimate is for planning purposes only. Actual costs may vary based on location, material prices, labor rates, taxes, fees, exchange rates, and project conditions.
📘 How it Works
This paint calculator estimates how much paint you may need for a room based on wall dimensions, doors, windows, coats, paint coverage, waste allowance, and paint price.
Wall Area: 2 × (Length + Width) × Height
Paintable Area: Wall Area − Door and Window Deduction
Coverage Area: Paintable Area × Number of Coats
Paint Needed: Area With Waste ÷ Paint Coverage
🎯 When to Use
- 🏠 Estimating paint for bedrooms, living rooms, offices, and hallways
- 🎨 Planning interior wall painting with one or more coats
- 🚪 Accounting for standard doors and windows before buying paint
- 🪣 Estimating paint containers based on coverage and waste allowance
- 💵 Comparing approximate paint cost in US or Canada mode
🎨 Paint Planning Guide for US Projects
Start with room dimensions
Enter the room length, room width, and wall height in feet. The calculator estimates wall area in square feet before subtracting standard door and window areas.
Use the paint label for coverage
The default coverage is 350 sq ft per gallon. Change this value if your paint can lists a different coverage rate.
Add a waste allowance
Use 5% to 15% for most interior painting projects to allow for touch-ups, surface texture, roller loss, and normal application waste.
Review full gallons and cost
Paint is normally purchased in full gallons, so the calculator rounds up the estimated amount and multiplies it by your price per gallon in USD.
❓ Paint Calculator FAQ
🧮 How many gallons of paint do I need for a room?
It depends on room size, wall height, number of coats, paint coverage, doors, windows, and waste allowance. This paint calculator combines those inputs to estimate gallons needed.
🪣 How many square feet does one gallon of paint cover?
Many interior paints cover about 300 to 400 square feet per gallon. The default is 350 sq ft per gallon, but you can edit the coverage value to match your product.
🚪 Should I subtract doors and windows?
Yes. Doors and windows reduce the paintable wall area. This calculator subtracts standard estimated areas before calculating paint needed.
🎨 How many coats of paint should I use?
Two coats are common for interior walls, especially when changing colors or painting over uneven coverage. You can adjust the number of coats.