How many square feet does a gallon of paint cover?

Standard paint covers approximately 350-400 square feet per gallon on smooth surfaces. Textured walls or porous surfaces may require 20-30% more paint. Premium paints typically offer better coverage.

How many coats of paint do I need?

Most rooms require 2 coats for complete coverage, especially when changing colors. Going from dark to light colors may require 3 coats. One coat is sometimes sufficient for touch-ups on the same color.

Should I subtract doors and windows from my paint calculation?

Yes. A standard door is approximately 21 square feet and a standard window is approximately 15 square feet. Subtracting these from your total wall area gives a more accurate paint quantity estimate.

How much extra paint should I buy?

Buy 10% extra for waste, touch-ups, and cutting in around edges. Having leftover paint also allows for future touch-ups if the paint batch is discontinued.

Paint Calculator: How Many Gallons Do I Need?

📐 Room Dimensions

Room Length (ft)

Room Width (ft)

Ceiling Height (ft)

🚪 Subtract Openings

Number of Doors

Number of Windows

⚙️ Options

Coats of Paint

Include Ceiling?

Paint Coverage/Gal

Gallons to Buy

— gallons

Paintable Area

—

sq ft

With Waste (10%)

—

sq ft

Est. Paint Cost

—

at $45/gal avg

⚠️ Don't get caught short Paint from different batches can vary in color — even with the same name and code. Buy everything you need in one trip, and keep one sealed can for touch-ups.

🛒 Supplies Checklist

Roller frame (9-inch)
Roller covers — get 2–3 (one per coat, plus a spare)
Extension pole (fits roller frame)
Paint tray + tray liners
2-inch angled brush (for cutting in)
Painter's tape (2-inch, blue or green)
Drop cloths or plastic sheeting
Small can of spackling for nail holes
120-grit sandpaper or sanding block
Primer (if painting over dark colors or new drywall)
Paint mixing sticks

Advertisement — 728×90

Want to save this calculation? Email it to yourself.

🎨 Paint Calculator