How to Calculate Square Footage of a Room
To calculate the square footage of a room, measure the length and width of the room, and convert those measurements to feet.
To convert length and width measurements, divide the inches portion of the measurement by 12 and add that result to the feet portion.
For example, if the length of a room measures 12 feet, 9 inches, divide the 9 inches by 12 (9 ÷ 12 = 0.75) and add it to the feet portion, for a total of 12.75 feet.
Or, if the length of a room measures 153 inches, divide the 153 inches by 12 (153 ÷ 12 = 12.75), and since there is no feet portion, the converted total would 12.75 feet.
Finally, once you have converted the length and width measurements to feet only, multiply the length feet by the width feet to find the square footage of the room. So if the length of a room is 12.75 feet and the width of the room is 10 feet, the square footage of the room would be 127.5 square feet (12.75 x 10 = 127.25).
The following chart from the results of the Price Per Square Foot Calculator shows how you would calculate and add up the square footage of multiple rooms.
| Area Label | Width | Length | Area Square Feet | ||
|---|---|---|---|---|---|
| Ft. | In. | Ft. | In. | ||
| Bathroom | 6 | 0 | 8 | 0 | 48.0 |
| Bedroom | 10 | 6 | 12 | 6 | 131.3 |
| Master Bedroom | 15 | 0 | 22 | 0 | 330.0 |
| Kitchen | 0 | 144 | 0 | 216 | 216.0 |
| Basement | 30 | 0 | 45 | 0 | 1350.0 |
| Total square feet: | 2075.3 | ||||
Note that you would calculate the square footage of any other square or rectangle area (floor, building, etc.) the same way as you would a room.
How to Calculate Price Per Square Foot
Once you know the square footage of a building, to find the price per square foot, you divide the price of the house or commercial building by the total square footage.
For example, if a 3,000 square foot house is listed at $250,000, the price per square foot would be $83.33 (250000 ÷ 3000 = 83.33).
How to Calculate Rent Per Square Foot
Once you know the square footage of an apartment, to find the rent per square foot, you divide the rental payment by the total square footage.
For example, if a 1,200 square foot apartment rents for $900 per month, the monthly rent per square foot would be $0.75 (900 ÷ 1200 = 0.75). To find the annual rent per square foot, multiply the monthly rent per square foot by 12 (0.75 x 12 = $9 per square foot annually).
How to Calculate Square Foot Price
If you know the price per square foot and the total square footage, you can calculate the square foot price by multiplying the price per square foot by the total square footage.
For example, if the price per square foot is $111.05, and the total square footage is 4,500, the square foot price would be $499,725 (111.05 x 4500 = 499725).
By the way, according to the U.S. Census Bureau Survey of the Median Price per Square Foot of new single-family homes, 2017, the average cost per square foot of new single-family homes was $111.05.
Note that you can use the same formula to calculate square foot rent or lease payments (rent per square foot x square footage = square foot rent payment).