Paint Calculator
A professional wall paint estimator. Enter room dimensions, number of coats, and coverage rate to find the exact paint volume required with adjustable safety waste margins.
1 · Project Specifications
Dimensions
Length of the room to paint.
Width of the room to paint.
Ceiling height of the room.
Specifications
Number of paint coats to apply.
Standard paint covers ~350-400 sq ft per gallon.
Options
Adds extra paint (10% recommended) to cover spillages and textured surfaces.
2 · Material Estimates
Estimation Results
Enter your measurements and click Calculate to see your estimate.
Detailed Project Guide & Calculation Methodology
Calculation Formulas & Methodology
Wall Surface Area Formula
Wall Area = 2 × (Length + Width) × HeightCalculates the total surface area of all four walls in a rectangular room.
Paint Required Formula
Gallons = (Wall Area / Coverage Rate) × Coats × (1 + Waste / 100)Calculates volume of paint needed based on wall square footage, coverage rate (standard is 350 sq ft/gal), coats, and waste margin.
How It Works
- 1Select your units for length, width, and height (feet or meters).
- 2Input the dimensions of the room layout.
- 3Specify the number of coats (2 coats is standard for most jobs).
- 4Choose a waste allowance percentage (10% is recommended for roll-on painting).
- 5Click Calculate to see your paint volume estimates.
Frequently Asked Questions
On average, a standard gallon of paint covers about 350 to 400 square feet. Porous walls, textured drywall, or dramatic color changes might require more paint.
For most painting projects, two coats are recommended for consistent color saturation, durability, and a professional finish without streaks.
Yes. We recommend adding a 10% waste allowance to cover roller absorption, brush retention, paint tray residue, and potential spillages.
✓ Pro Tips
- •Always purchase slightly more paint than calculated to cover touch-ups later; color matching can vary between batches.
- •If you are painting over a dark color with a lighter shade, apply a coat of white primer first to reduce the number of premium paint coats required.
- •Wrap brushes and rollers in plastic wrap or bags between coats to keep them from drying out without needing to clean them.
⚠ Common Mistakes
- •Forgetting roller absorption: Rollers and brushes soak up a significant amount of paint. Failing to factor in a 10% waste margin will leave you short.
- •Skipping wall height measurement: Estimating solely based on room square footage ignores ceiling heights, leading to highly inaccurate calculations.
- •Painting textured walls without adjusting: Textured or stucco walls have more surface area and can consume up to 25% more paint.
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DIY Estimation Checklist
- •Measure lengths and heights twice for accuracy.
- •Check product labels for actual coverage rates.
- •Order materials with a 10% buffer for cuts and waste.
- •Account for doors, windows, and obstacles.
- •Compare quotes from at least two suppliers.