Skip to Main Content

How much paint do I need?

Before choosing the paint color for your next home improvement project, first determine how much paint you will need to cover your space. To do this, simply measure the room you want to paint, enter the measurements in Bankrate's calculator to the nearest foot, and click "calculate" to see your estimate.

How to calculate how much paint you need

To calculate how much paint you need, start by measuring the width of each wall as well as the height of the room from floor to ceiling. Include the ceiling dimensions if you plan to paint it, too. 

Find the square footage of triangular or sloping walls – like in rooms with vaulted ceilings – by multiplying the length of the base of the triangle by the height at the highest point and dividing by two.

To make sure you have enough paint, do not subtract any square footage for windows and doors unless they significantly reduce the square footage of that wall.

How many square feet does a gallon of paint cover? 

Most typically, a gallon of paint covers anywhere from 350 to 400 square feet, so a gallon of paint is enough to cover a small space like a bathroom. Depending on the number of coats you intend to paint, one to two gallons of paint is the average amount for a typical sized room. To be most precise, consult the manufacturer's advice on the label. 

How much primer do you need?

Primer is essential when you paint a room. Like paint, a gallon can cover 350 to 400 square feet. You can use the same result from the calculator to determine how many gallons you need per coat of primer. However, the amount of coats you choose to apply will depend on a few factors.

  • Drywall and unfinished walls may require two coats of primer to help the paint absorb more evenly.
  • Dark or bright colors may also require two or even three coats of primer. To cancel out the previous color, you may need to request a tinted primer from your paint store.
  • Neutral colors should need one coat of primer to prep the wall for your new color choice.

How much paint do you need for a bedroom?

The size of bedrooms varies but averages around 800 square feet, which means you will need two to three  gallons of paint for every coat. This being said, it is best to use a calculator to find the exact amount of paint needed for your space. Primer and trim paint should also be calculated when you paint a bedroom — or any room — and you may want to include your ceiling in the calculation if it needs to be freshened up.

How much paint do you need for trim?

Trim takes up less real estate in a room than walls but can be significantly harder to calculate. To get an accurate measure, you will need to know the length and width of each piece of trim. Add together the baseboards, crown molding as well as any doors, door frames and window frames. 

In general, you may be able to get away with a few quarts of paint for trim depending on how many coats you plan on doing. However, purchasing a full gallon or two will help you avoid multiple trips and incorrect color matches. Paint can be stored for up to five years, so you will be able to use it again for touch ups or other rooms in the future.