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Estimate paint coverage using a paint calculator

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Buying the correct amount of paint reduces the quantity of leftover paint, much of which ends up in landfills or is sometimes dumped down the drain. You will also save money by not over-purchasing.


How to buy the correct amount of paint

Determining the amount of paint you’ll need for a project by measuring the space and calculating the number of square feet to be painted (height multiplied by width) ensures you purchase only what you require. A gallon of interior paint typically covers approximately 400 square feet, but that can vary by type of paint and wall surface.

Ask a paint specialist or retailer for help with your calculations, or visit online paint calculators where you take the measurements, plug in the numbers, and are returned a grand total. Here are a few you might want to check out:

Find it! Paint samples

Take the risk out of choosing color by buying (or getting free!) paint samples to try out on your very own walls. Even if you can't get a sample of your favorite low- or no-VOC paint, you could always try a conventional paint sample and then have that color-matched with your nontoxic brand of choice.

Buying the correct amount of paint helps you go green because…

  • Less paint is consumed, saving resources and preventing paint waste from being sent to landfills.
  • Fewer taxpayer dollars and energy will be spent on cleanup of leftover paint collections.

Americans purchase a lot of paint. Each year an average of two gallons of household paint is sold for every person in the US.[1] More than 850 million gallons of indoor and outdoor paint was sold for use on residential, commercial, institutional and industrial buildings in 2005.[2]

Of all this paint, a good deal of it isn’t used. A new US Environmental Protection Agency (EPA) study estimates that approximately 65 to 69 million gallons (or about 10 percent) of house paint purchased in the US every year is discarded. Leftover paint is the largest volume material collected by most household hazardous waste collection programs across the country.[3] Managing this paint costs municipalities an average of $8 per gallon.[4] Careful measurement of areas to be painted is the best way to accurately estimate your paint needs per project to avoid buying too much and to decrease the amount of paint that ends up in your local landfill.

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