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How to Estimate the Amount of Paint You Need for Your Paint Project

How to Estimate the Amount of Paint You Need for Your Paint Project

Looking to paint a room in your house but not sure how much paint to buy? Find out how much paint you need using our guide.

Estimate your room size and paint needs before you go to the paint store because running out of a custom color halfway through the job would be terrible.

How Much Paint Is Needed for my Paint Job?

  • Start by adding up the length of all the walls to be painted, from end to end.
  • Then multiply this number (the perimeter) by the height of the walls, from floor to ceiling. That will give you the square footage of the room to be painted.
  • Finally, divide your total number by the approximate coverage of one gallon of paint (about 400 sq. ft. per gal.). This gives you how many gallons of paint you need for one coat of paint on the walls.

How Much Paint Is Needed for Trim?

A room’s baseboards, windows, doors, and crown molding are often painted in a different finish or color than the walls and ceiling, so you can calculate your trim paint needs separately.

  • Add up the length of all the trim to be painted, then add up the width of all the trim. (You may need to do this by trim type if they’re not all the same widths.)
  • Multiply length x width to get the square footage of trim to be painted.
  • Divide the total by 400 to get the number of gallons of paint you’ll need for one coat. You’ll likely need less than a gallon for a standard room, so consider buying trim paint in a quart or two.

Do I have to prime before painting?

It’s almost always a good idea to prime first, and priming is a must when painting a lighter color over a darker color, or painting over new drywall or unfinished wood. That said, when using a color similar to the existing one and a paint that is similar chemically (latex over latex, for instance), you might be able to skip priming.

Follow these formulas to create the perfect finish for your project every time. Using these formulas helps to ensure that you are working with just enough paint—not too much or too little. This will save you time, money, and effort in the long run. With a bit of practice, anyone can become an expert at calculating how much paint

If you need interior or exterior painting services, give the experts at Rossi Painting a call today!

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