How to measure a room for your renovation project?

how to measure a room

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.

Measuring tape measurement

The most common method of measuring a room is with measuring tape, usually one with a 25-foot tape and a fastener (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 inaccurate measurement.

Laser tape measurement

If this proves frustrating (and it does to some), consider a laser tape measure. Though they are pricier than the manual type (about $40 to 60), they can cut the time of labor in fractions and produce very accurate measurements, within 1/16th of an inch. Just place the laser tape measure on one side of the room, and face the laser on the opposite wall. Once the laser point is visible, the press of a button will measure the distance (including the length of the laser tape measure itself).

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Foot Measurement

When neither of the above-mentioned methods on how to measure a room is at your disposal, your feet can double as a valuable measuring tool. After closely measuring the length of your foot, you start on one side of the room and carefully put one foot in front of the other, with the one in back flush against the wall. Walk heel to toe until you’ve reached the other side of the room, counting 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

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 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 area 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.

MORE: How to Paint Kitchen Cabinets in 5 Easy Steps

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