Paint Calculator
To calculate paint needed: find total wall area (2 × (length + width) × height), subtract doors (~20 sq ft each) and windows (~15 sq ft each), multiply by number of coats (usually 2), then divide by coverage per gallon (typically 350 sq ft). A standard 12×12 bedroom with 8 ft ceilings needs about 2-3 gallons for two coats.
Calculate how much paint you need for any room. Enter room dimensions or wall-by-wall measurements, subtract doors and windows, choose number of coats, and get gallons needed with cost estimate. Supports multiple rooms, imperial/metric units, and room presets.
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Settings
Imperial (ft)Metric (m)
Room 1
Presets:
How to Use
- Enter your value in the input field
- Click the Calculate/Convert button
- Copy the result to your clipboard
Frequently Asked Questions
- How much paint do I need for a room?
- Calculate total wall area: 2 × (length + width) × height. Subtract doors (~20 sq ft each) and windows (~15 sq ft each). Multiply paintable area by the number of coats (usually 2). Divide by paint coverage (typically 350 sq ft per gallon). For a standard 12×12 room with 8 ft ceilings, you need approximately 2-3 gallons for two coats.
- How many square feet does a gallon of paint cover?
- One gallon of paint typically covers 350-400 square feet per coat. This assumes smooth, primed walls. Rough or textured surfaces, unprimed drywall, and porous surfaces may reduce coverage to 200-300 sq ft per gallon. Always check the paint can label for the manufacturer's recommended coverage rate.
- How many coats of paint do I need?
- Most walls require 2 coats of paint for even coverage. You may need 3 coats when painting over a darker color with a lighter one, using bold or deep colors, or painting new drywall. One coat may suffice if using paint-and-primer-in-one over a similar color on already-painted walls.
- How do I calculate paint for doors and windows?
- Standard interior doors are approximately 20 square feet (3 ft × 6.8 ft). Standard windows average about 15 square feet (3 ft × 5 ft). Subtract these from your total wall area before calculating paint needed. A typical bedroom has 1 door and 2 windows, reducing paintable area by about 50 square feet.
- Should I buy extra paint?
- Yes, always buy 10-15% more paint than calculated. Extra paint accounts for touch-ups, waste, and uneven application. Keep leftover paint sealed tightly for future touch-ups — properly stored latex paint lasts 2-10 years. It's better to have a little extra than to run out mid-project and risk color batch differences.
- What is the difference between imperial and metric paint coverage?
- In imperial units, coverage is measured in square feet per gallon (typically 350 sq ft/gal). In metric, coverage is measured in square meters per liter (typically 10-12 sq m/L, or about 32.5 sq m per gallon equivalent). One gallon equals 3.785 liters. The actual paint performance is the same regardless of measurement system.