Paint Calculator
Estimate the amount of paint needed for a room based on dimensions, windows, and doors.
Published by:
isCalculator Editorial Team
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How to use this tool?
How to Use the Paint Calculator
This calculator estimates the gallons of paint needed for a rectangular room. All measurements are in feet (imperial system).
- Enter room dimensions: Input the room's Length, Width, and Height in feet (e.g., 12, 10, 8). Use positive numbers only.
- Specify openings: Enter the Number of Windows and Number of Doors (non-negative integers). Each window deducts 15 sq ft, each door deducts 20 sq ft.
- Set coats: Enter the Number of Coats (minimum 1).
- Calculate: Click the "Calculate Paint Needed" button.
- Read results: The output shows:
- Paint Required in gallons (rounded to the nearest half gallon).
- Detailed breakdown: total wall area, deductions, net area, coats, and total coverage.
Note: 1 gallon covers 350 sq ft. Ensure all inputs are valid to see results.
Previous Results
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Frequently Asked Questions
It calculates total wall area by multiplying perimeter by height, subtracts 15 sq ft per window and 20 sq ft per door, multiplies by number of coats, then divides by 350 sq ft per gallon (standard coverage).
We assume one gallon covers 350 square feet. Actual coverage may vary by paint type and surface.
This calculator is designed for interior walls. For exterior, consider different coverage rates and subtract window/door areas accordingly.