Painting your home is a fun and easy way to spruce up your living space. However, it does require some proper planning if you are going to do the job right. Before beginning any painting project, it is important to figure out how much paint you’ll need, as the only thing more frustrating than running out of paint halfway through is completing your task only to find you have lots of leftover paint and nothing to do with it.

Calculating how much paint you’ll need is a fairly simple task. First, you have to determine what type of surface you’ll be painting on. A smooth, even surface will require a lot less paint than a rough or cobbled surface, which will soak up paint and require extra coats.

Most paint producers provide guidelines regarding how much of their paint is needed to cover a certain amount of square footage, but for most paints, you can assume that one can of paint cover, at the most, about four hundred square feet, assuming you are putting on one coat. For rougher surfaces, you can assume coverage of about one-hundred-fifty to two hundred square feet.

Now that you know how much a gallon of paint covers you need to calculate how much square footage you are trying to cover. This requires some simple calculations. For blank walls, without windows, measure the width of the wall by the height. Multiply the two numbers this is your square footage.

For example, if a blank, windowless wall is fifteen feet wide by ten feet high, you would multiply fifteen by ten, for a total of one hundred fifty square feet. If the surface is smooth, you should need less than a half-gallon of paint for that particular wall; if textured, about a gallon. Of course, you need to do this for all of the walls that you are painting, and then add up the total square footage before deciding how much paint to buy.

But what if you have windows or doors? No problem. Simply calculate the square footage of the window or door by multiplying the height and width of the window or door frame, then subtract that from the total square footage. For example, let’s say you have a window in the wall of the earlier example three feet wide by six feet high. Multiply three by six to get eighteen square feet, then subtract that from the total wall space.

In our previous example, the wall space was one hundred fifty square feet. Subtract eighteen square feet from that for the window and you discover that you only need to cover one hundred thirty-two square feet. Repeat this for all of your windows, doors, and any other non-removable objects you will not be painting, such as built-in wall hutches or medicine cabinets.

Again, remember that you may need more or less paint depending on the surface you are painting. If a wall has been painted previously, for example, you may need extra coats of paint to cover the old color.

Allow for this when you are making your calculations, and as always, feel free to discuss your particular project with the paint store employee, who will know more about the specifics of the brand of paint you are buying and your particular project.