Paint Calculator

Find out how many gallons of paint to buy. Measure the total wall area, choose your number of coats, and subtract large openings if you like.

How the Math Works

The Paint Calculator uses a simple formula to estimate paint needs: gallons = area × coats ÷ coverage. Here, 'area' represents the total surface to be painted (length × height for walls), 'coats' is the number of layers required, and 'coverage' is the square footage a gallon of paint can cover, typically listed on the paint can. Multiplying area by coats gives the total square footage to be covered, which is then divided by coverage to determine the number of gallons needed. This ensures precise calculations by accounting for both surface size and application thickness.

Practical Applications

To apply this calculation, first measure the length and height of each wall to determine total area, subtracting spaces like windows or doors. Decide how many coats are needed based on color changes or surface condition. Check the paint can's coverage rating (usually in square feet per gallon). Input these values into the calculator to avoid under- or overbuying. For textured surfaces, consider increasing the required gallons by 10-20%, as rough finishes consume more paint. Always round up to the nearest half-gallon to ensure sufficient supply.

Day-to-Day Use

This calculator simplifies home projects by providing accurate paint estimates, saving money and reducing waste. Instead of guessing or making multiple store trips, users can plan purchases confidently, whether painting a single room or an entire house. It also helps contractors bid jobs more precisely, improving client satisfaction and project timelines. By preventing shortages mid-project, it eliminates last-minute delays and ensures a smooth, professional finish for DIY enthusiasts and professionals alike.

Worked example

400 ft² with 2 coats at 350 ft²/gal → 800 ÷ 350 = 2.3 → 3 gallons.

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