Whether you’re determining the perfect size for that addition to your home, deciding how much carpet to purchase, or figuring out how big your new sofa can be without making your living room cramped, knowing how to measure a room and calculate square footage is a necessary part of creating your ideal space. There are techniques that range from the very rough to the very precise, and each of them has its own purpose.
Measurement with a measuring tape
The most common method of calculating the square feet of a room is with a measuring tape. For any square or rectangular room, you can use a 25-foot tape and a fastener — since most rooms are under 25 feet in length or width. Though these are not ideal for single operators, you can latch the front end of the tape to a stable ledge on one side of the room and slowly pull it back until it has reached the other side. An inherent flaw in tape measures is their tendency to bow and bend when stretched across long distances, resulting in the occasional fluctuations of correct measurements.
Laser tape measurement
If the above method proves frustrating (and it does to some), consider a measuring the area of the room with a laser tape. Though laser tapes are pricier than the manual types (about $40 to $60), they can cut the time of labor into fractions and produce very accurate measurements, within 1/16th of an inch. Just place the laser tape on one side of the room and face the laser on the opposite wall. Once the laser point is visible, a single press of the button will measure the distance (including the length of the laser tape itself).
When neither of the above-mentioned methods on how to measure a room is at your disposal, your feet can double up as a valuable measuring tool. After closely measuring the length of your foot, you can start on one side of the room and carefully put one foot in front of the other, until you reach the other side. In the process, count the number of footsteps out loud. Multiply the number of footsteps by the length of your foot in inches, then divide by 12 to get the measurement in feet.
Once you find the technique that fits your needs, measure both the length and width of your room, making sure that you create a line perpendicular to the walls on either end. Most rooms are rectangular, so making a line parallel to the adjacent wall works just as well.
Watch: Calculate the square footage of a rectangular room
How to measure a room that is not square or rectangular?
If your room is not a rectangle, then divide it into different shapes (circles, triangles, smaller squares, or rectangles). You can sketch it out to help you visualize the space and divide it up, or use a painter’s tape to divide the room into different areas/shapes. From there, you can take the measurements of each shape.
If you have trouble drawing up plans or figuring out how to accurately divide space, check out this write-up on how to work with an architect. The added experience can be immeasurably valuable, especially for larger projects.
Watch: Calculate the square footage of an L-shaped room/divide a room into different spaces
After all the measurements have been taken, it’s time to do some math. For rectangular spaces, simply multiply the length and width of the room to calculate the total areas or square footage. For square spaces, do the same, although you’ll have the same measurement for length and width. Other shapes require different formulas:
- Triangles: Area = 1/2 base x height
- Circles: Area = π (pi) x the radius squared (radius x radius)
- Semicircles: Area = π (pi) x the radius squared (radius x radius), then divide by half
Once you’ve calculated the area of each shape, add them together to get the total square footage of your room, and you’re done.
Remember when you’ve completed these projects, always record the data in an organized manner. Many first-time renovators take on more projects after they have completed their first, and having this information on how to measure a room on hand can save a headache or two in the long run.