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Measure a Room

Find useful tips on how to measure standard, rectangular rooms and odd-shaped rooms with a few simple tools. Knowing how to correctly measure a room will make projects, like flooring and painting, easier and more cost-effective.

Measure a Room

How to Measure Area and Perimeter

Measure Area and Perimeter

To measure the area and the perimeter of a standard square or rectangular room, you can always use the simple formulas below.

(Length) x (Width) = Area

(Length) + (Width) = Perimeter

Rectangular and Odd-Shaped Rooms

Odd-Shaped Rooms

To measure your rectangular room, use a tape measure, pencil and paper to record the length and width of the room. Once you have these two measurements recorded, multiply them to get the total area of the room. 

If the room you're measuring has a recess or protrusion, such as a closet or bay window, measure the shortest length and width of the room first.  Then multiply them to get the main area of the room. After you've recorded the number, calculate the area of the individual recesses by measuring their length and width.  Lastly, add all of the areas together to get the total area of the room. You'll use this same process for T-shaped and L-shaped rooms as well.

When calculating the area of U-shaped rooms, use the same method of adding the individual areas together, except when measuring the area of a round recess. To calculate the area of a round recess, measure the longest width and length of the recess, normally through the center of the space first. Next, divide the length in half and multiply that number by the width. Once you have this calculated, multiply the total by pi (3.14). This will give you the area of the complete circle. However, only half of the circle extends beyond your wall, so divide the area in half. Now you have the area of the U-shaped protrusion in your room. You can add this number to the area of the other measurements in your room for the total area.


Measure Walls

To calculate the area of a wall, use the standard formula of (Length) x (Width) = Area. Next, use the same formula to record the individual area of windows and doors. Once you have all of these measurements down, subtract the area of the windows and doors from the total area of the wall. This will help you calculate how much paint or wallpaper you need for a room without having lots of excess when you're finished.

Measuring Tips

  • Ask a friend to help you take measurements. One of you can record while the other measures.
  • Make sure there are no obstructions or obstacles that will throw your measurements off.
  • Include a buffer of about 15% when purchasing materials. This will protect you from any unforeseen miscalculations and keep you from running short on supplies in the middle of your project.