Buying the right amount of paint for a project seems simple — figure out how big your room is, look to see how many square feet a particular can covers, and buy accordingly. As anyone who has ever painted a room has probably discovered, though, it’s not quite that easy.
There are many factors that influence how much paint you need. Consider the following:
The Size of the Room
This is the most obvious consideration — what’s the surface area of the walls of the room you’re painting? Remember to subtract out spaces for doors and windows if they aren’t being painted the same color. If the coverage on the can says 300-400 square feet, you need 1 gallon for a typical room (10 feet by 10 feet) with smooth walls.
The Use of Primer Beforehand
You may think using primer for a base coat is unnecessary, but it’ll make your paint job better, and you won’t need as much paint — especially for new walls that have never been painted. Considering that paint is more expensive than primer, you will save money in the end to use primer first. When changing the color from dark to light, use white primer; when changing from light to dark, ask your paint dealer to tint it to gray.
The Texture of Your Walls
“If the surface is rough, it takes more paint to cover it,” says Paul Fresina of PaintCare, a nonprofit organization that works with state and local governments to make paint recycling easier for consumers.
The Color of Your Paint
Here’s a fun fact: If you use red paint, you’ll usually need more than with any other color. Other colors, too, may require extra layers. Also consider the colors you’re starting and ending with. If you’re going from a really dark color to a light color or vice versa, the color change means that you’ll probably need more coats.
The type of paint. The old adage of “you get what you pay for” applies to paint. “If you buy cheap paint and it doesn’t cover as well and you need more paint, you’re not saving money in the end,” Fresina says. “It’s faster and usually saves money to use higher-quality paint.” The more solids in a paint, the better it will cover.
With all these considerations, it’s best to ask your salesperson for assistance — they can advise you on approximately how much paint you need based on the kind you’re buying and what you’re painting.
Yet no matter how well you estimate, you may not be able to buy paint in the exact increment you need. “Unless you intentionally use up the paint by putting on an extra coat, you almost always have some left over because of the fact that it’s only sold in certain-sized containers,” Fresina says. Keep some paint around for touch-ups, and if you have a lot left over, you can find creative ways to use it up or look at recycling options.