Paint Calculator
Calculate how many gallons or liters of paint you need for a room.
Enter room dimensions and get accurate paint estimates including doors and windows.
Paint Needed
Paint Coverage is calculated by finding the total wall area, subtracting openings, and dividing by the paint coverage rate.
Wall Area = Perimeter × Height
Imperial formulas:
Paintable Area = Wall Area − (Doors × 21 sq ft) − (Windows × 15 sq ft)
Gallons Needed = Paintable Area / Coverage per Gallon
Metric formulas:
Paintable Area = Wall Area − (Doors × 1.95 m²) − (Windows × 1.4 m²)
Liters Needed = Paintable Area / Coverage per Liter
Typical coverage rates:
- One gallon covers about 350–400 sq ft (one coat)
- One liter covers about 10–12 m² (one coat)
Practical tips:
- Most rooms need 2 coats — this calculator accounts for that
- Dark-to-light color changes may need a primer + 2 coats
- Textured walls use 10–15% more paint
- Standard door: ~21 sq ft (~1.95 m²), standard window: ~15 sq ft (~1.4 m²)