Interior Painting – How to calculate how much is needed

Mitchell & Best Homes

Mitchell & Best Homes

One of the most exciting parts of buying or personalizing a house is painting the interior – to make your living space a true reflection of your personality and values.

If you decide to paint indoors, it’s important to calculate the amount of paint you’ll need, as well as some helpful tips to get you started.

How much paint do I need?

McCormick Paints recommends one gallon of paint per 300 square feet of interior. For an easy reference, you can use our paint calculator.

Once you know the total square footage of the room you want to paint, subtract the square footage of windows and doors in that space. Don’t forget to include the square footage of a door if you plan to paint it. The average door takes up about 20 square feet, and the average window takes up about 15 square feet. 

Once you’ve subtracted windows and doorways from the square footage, divide by 300 to estimate how many gallons of paint you need. For example, a 600-square-foot room needs two gallons of McCormick paint to be adequately covered.

Overestimating the amount of paint you need is probably a good idea for the because:

  • You won’t have to worry about going back to the store for more paint.
  • You have a little more leeway to apply multiple coats of paint. If you’re painting a surface that absorbs paint heavily, such as drywall, this can be important.
  • Left-over paint can be used to patch up imperfections, such as scrapes, chips, etc., in the coming years as your interior experiences wear and tear.

Interior painting 101: the basics

Now, let’s go over some handy interior painting tips to get you started:

  • Paint the trim first. To paint the trim and windowsills of a room a different color, put down rosin paper against the base of the trim to protect the floor and paint the trim first. This way, you can get paint from the trim on the wall without worrying about it.
  • Tape your trim and windowsills. Once the trim and windowsill paint has dried, place painter’s tape over these areas. This allows you to paint up to and around the trim and sills without discoloration. Once the wall paint is dried, carefully cut away the painter’s tape to prevent the tape from taking paint from the walls as it comes off.
  • Patch holes, clean and prime walls. You’ll want to clean your walls using something like a magic eraser, patch up holes or imperfections, and prime walls with a primer paint before moving onto your desired color.
  • Use long strokes. Using a paint roller with a long handle can allow you to cover the entire wall with one stroke. This is important since it prevents “lap marks,” where strokes of paint overlap.

There you have it … everything you need to know about calculating how much paint you need for interior painting. To get your hands on the best-quality paint around, visit the McCormick Paints website.