Free Paint Gallons Calculator
Calculate how many gallons of paint you need with automatic deductions for doors and windows. Includes wall perimeter, height, and coat settings.
feet
feet
sq ft/gallon
Gallons Needed
2
Gross Wall Area448 sq ft
Deductions (Doors/Windows)102 sq ft
Net Paintable Area346 sq ft
Gallons Needed vs Coverage Rate
How to Calculate Paint Gallons with Deductions
Formula
Net Area = (Perimeter × Height) - (Doors × 21 sq ft) - (Windows × 15 sq ft)
Gallons = (Net Area × Coats) / Coverage Rate
A standard door opening is about 3 ft × 7 ft = 21 sq ft. A standard window is about 3 ft × 5 ft = 15 sq ft. One gallon of paint covers approximately 350 sq ft.
Example Calculation
A 14×14 ft room (56 ft perimeter), 8 ft ceiling, 2 doors, 4 windows, 2 coats.
- 01Gross wall area = 56 × 8 = 448 sq ft
- 02Door deductions = 2 × 21 = 42 sq ft
- 03Window deductions = 4 × 15 = 60 sq ft
- 04Net paintable area = 448 - 42 - 60 = 346 sq ft
- 05Gallons = 346 × 2 / 350 = 1.98 → 2 gallons
Frequently Asked Questions
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