Technical Free

Paint Coverage Calculator

Estimates gallons of paint needed based on area, surface type, number of coats, and application method. Accounts for coverage rates and wastage.

Use the Wall Area Calculator if unsure.

Results

Total Gallons
--
Per Coat
--
gallons
Cans Needed
--
Est. Paint Cost
--
Coverage rate used--
Wastage factor--

Coverage rates based on manufacturer data. Actual coverage varies by product, technique, and surface condition. Always check the can label.

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How to Use This Calculator

1. Enter the total paintable area. Use the Wall Area Calculator to measure your room, or enter a known square footage directly.

2. Select surface type. Smooth drywall has the best coverage. Textured surfaces, masonry, and stucco absorb more paint and reduce coverage per gallon.

3. Choose paint type and coats. Latex is standard for interior. Two coats is the industry standard for a quality finish.

4. Pick your application method. Rollers waste the least paint (5%). Sprayers are fastest but waste 15%. The calculator adjusts coverage accordingly.

How the Coverage Formula Works

Adjusted_Coverage = Base_Coverage / Wastage_Factor

Gallons_per_Coat = Area / Adjusted_Coverage

Total_Gallons = Gallons_per_Coat x Number_of_Coats

Round up to nearest 0.5 gallon

Base coverage rates come from manufacturer data (Sherwin-Williams, Benjamin Moore). Latex on smooth drywall covers 400 sq ft/gal, while masonry drops to 250 sq ft/gal due to porosity and surface texture.

Frequently Asked Questions

How much paint do I need for a room?
Divide the total paintable square footage by the paint's coverage rate (typically 350-400 sq ft per gallon for latex on smooth drywall). Multiply by the number of coats. Add 5-15% for wastage depending on your application method. A typical 12x10 room with 8-ft ceilings needs about 2-3 gallons for 2 coats.
How many square feet does a gallon of paint cover?
A gallon of latex paint covers approximately 350-400 sq ft on smooth drywall. Coverage drops to 250-300 sq ft on textured surfaces and masonry. Oil-based paint averages 350 sq ft per gallon. Always check the manufacturer label for the specific product you are using.
Should I use brush, roller, or spray?
Rollers are most efficient for large flat surfaces with only 5% waste. Brushes are best for trim and detail work but waste about 10%. Sprayers cover fastest but waste 15-25% of paint through overspray. Most interior jobs use a roller for walls and brush for cutting in edges.
How many coats of paint do I need?
Two coats is standard for most interior jobs. You may need 3 coats when covering dark colors with light, using a low-opacity paint, or painting porous surfaces. One coat may suffice for touch-ups using the same color, or when using a high-quality paint-and-primer-in-one product.

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