Buy too little paint, and you’ll run out in the middle of your project. Buy too much paint, and you’ll waste money and have leftover paint that you don’t need. This is why calculating how much paint you need is important. But don’t worry. It’s easy if you know the formula.
Rule of Thumb
One gallon of paint typically covers 350 to 400 square feet. Sometimes it may cover as little as 250 square feet. It depends on the surface you’re painting on and how it reacts to paint. Nevertheless, you need to calculate the total square footage of the area you plan to paint to determine how much paint you need. Then, adjust the number accordingly, depending on how many coats you’re going to apply.
To find out how many gallons of paint you need, simply calculate the square area that you need to paint and divide it by 400. Then multiply that number by the number of coats you need. You can do the exact same calculation for primer, too.
How Do I Calculate Paint for Walls?
Calculating how much paint you need is a breeze if you know what to do. Grab a tape measure (and perhaps a calculator) and get started.
- Measure the length of each wall in the room in feet.
- Measure the height of the walls in the room in feet.
- Multiply the length and width of each wall to get the square footage of each.
- Add the square footages of each wall together to get the total square footage.
- Subtract the square footage of all doors and windows in the room from the sum.
- Divide the sum by 400 to get the number of gallons you need.
- Multiply that number by the number of coats you need.
When you measure the length of your walls, be sure to exclude:
- Baseboards
- Molding
- Trim
- Anything else you don’t want to paint
How Many Coats of Paint Should I Apply?
Another thing you have to account for is the amount of coats you’ll use. One coat of paint is rarely a good idea. The number of coats you choose to use depends on the desired finish and the quality of the paint. Generally, two coats are recommended for smooth and even coverage.
However, if you’re using high-quality paint or if the walls have imperfections that require additional coverage, you may need to apply three coats. You’ll also need to apply multiple coats if you use all-in-one paint.
Which Paint Should I Use?
You can get the right amount of paint, but if you get the wrong kind, it will be of no use. There are different paint types; some are more suitable for wood, while others are better for metal or concrete surfaces. You also need to consider which paint to use depending on the area of your home. Some paints are suitable for bathrooms, others for garage floors, and yet others for exterior wood projects.
Choosing the right paint for the specific surface you’re painting is important. It will help you achieve proper adhesion and durability.
FAQ
Does open paint go bad?
Yes, left over, open paint will go bad. However, depending on the paint you’re using, it may last one to two years if you properly reseal it and don’t expose it to air. Check out our guide for more information on how long paint lasts and how to tell if it’s expired.
What if I apply too much paint?
If you apply too much paint, it can drip, cover unevenly, and take longer to dry. It’s important to follow the recommended application instructions and apply multiple thin coats if needed.
How do I clean up paint spills?
If you’ve spilled paint, you should act quickly to clean it up. Check out our How to Clean Up Spilled Paint guide to learn more. You can also use a tarp or a drop cloth to prevent spills in the first place.
DIY or Hire a Pro
To calculate how much paint you need, divide the square footage of the area you want to paint by 400. The sum you get is the number of gallons you need to buy.
But it’s not always a smart idea to turn your painting jobs into DIY projects. If you need help, get in touch with a painting pro in your area.
Main Image Credit: severija / Canva Pro / License
