How to Measure a Room
How to Measure a Room
Depending on the purpose that you are measuring the room for, there are different measurements that need to be taken. For example, if you’re putting in flooring, you need to know the area of the floor. If you are painting, you need to know the area of the walls and ceiling. And if you’re putting in a border of some sort, you need the perimeter measurement of the room. This can be difficult if you’ve never done it before, and can be complicated by built-in features like sloping ceilings, fireplaces, recesses, and bay windows. Find out how to do it here! Steps
Rectangular Room
Floors
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Make a drawing of the floorplan in the room you are measuring. It doesn’t have to be to scale, but the more accurate it is, the more useful it’ll be for recording purposes. In this hypothetical drawing, there is a bathroom on the right (which is a separate room, so it is not recorded in the measurement) and a bay window to the left.
- Measure the shortest width and length in the room. (See Tips if measuring for carpeting.) If you’re measuring a room with no recesses or foyers, there will be only one width and only one length. But in this example, three lengths are shown. The shortest one should be recorded. The other two, with the red line crossing through them, should not.
- Multiply the width and the length to get the main area measurement. If the room has no recesses or foyers, stop here. This is the measurement of the total floor area. Record this in the center of your drawing.
- Calculate the area of individual recesses.
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Square or rectangular recesses: Measure the width and length (shown in purple) of the recess (shown in green) as if it was a tiny room. Multiply the width and length to find the area of the recess. Record it in the recess area of your drawing.
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Round recesses: Measure the longest width and length of the recess (usually through the center) up until the edge of the main area, which you already measured. In this example, the length is shown in gold and the width in blue. Cut the length in half, and multiply your answer by the width, then by pi (3.14). This will give you the area of an entire ellipse, but remember that only half of the ellipse extends beyond the border of the room, so divide the area in half. Record this in the recess area of your drawing.
- This calculation is only accurate if the ellipse is divided in half by the wall. Otherwise, it is a rough estimate.
- The area in a bay window recess should only be included as part of the area of the room if it has a floor (rather than a seat) and the ceiling is at least seven feet or 2.13 m high.
- Add all of the areas together to get the total floor area.
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Ceilings
- Calculate the floor area as described above.
- Account for any differences between the floor and the ceiling area. If the outline is the same, the area will be the same.
- A ceiling that slopes or has recesses or variation of any kind will have a larger surface area than the floor, so keep that in mind (i.e. buy a little extra paint!).
- Skylights can be subtracted from the ceiling area. Multiply the length and width of the skylight to get its area, then subtract that amount from the total ceiling area to get a more accurate measurement.
Walls
- Make a drawing of the wall roughly to scale, including doors and windows.
- Measure the width and height of the wall.
- Multiply these together to get the total wall area.
- Subtract the area of windows and doors from the total wall area. If you’re measuring to see how much paint you’ll need, include the frames in your measurements (presuming the frame will be painted in the same color as the walls).
- Subtract the area of attached fixtures from the total wall area. This will be tricky, depending on the shape of the fixture (e.g. a sink will be more difficult than a standard bathtub).
Perimeter
- Measure a rectangular room by adding the length and the width and multiplying the answer by two.
- Measure a room with an irregular perimeter by working your way around with a measuring tape along the floor. If where the ceiling meets the wall is irregular (i.e. not a right angle) then the perimeter will be a little longer than on the floor.
Todd Kreps, Realtor/Broker/ABR/SRES
704.564.6941


