Formula for square footage
The formula for figuring out the square footage of a rectangular area, room, or house from measurements in feet is:
Square feet = Length (in feet) Width (in feet)
If the area or room you want to measure isn't a rectangle, we'll show you how to measure different shapes, including "L" shapes, below.
Weight is also important with the area in our daily routines. We usually don't think about the weight of what we purchase in our daily lives. Pounds and Kilograms are the two main weight measurements. Some companies indicate the weight in Pounds and some in Kilograms. It's easy to convert from Pounds to Kilograms.
We'll start with the most basic way to measure and figure out the square footage of a room or area that has a common shape. Before we do this, we need to talk about units. For these math problems to work, you need to measure in feet. If they aren't already in feet, you'll need to do the following to change them:
For feet, divide the number of inches by 12
For yards, multiply by 3, and for feet, add 1.
For feet, divide the number of cm by 30.48.
For feet, multiply m by 3.281 to get feet.
For yards, multiply by 3, and for feet, add 1.
For feet, divide the number of cm by 30.48.
For feet, multiply m by 3.281 to get feet.
How to figure out a square foot
For a room or area that is square or rectangular, measure the length and width in feet. Then, add together the length and width numbers. If your room is 14 feet wide and 18 feet long, for example, you multiply 14 by 18 to get 252 square feet.
To figure out how big an area is in square feet, you need to measure its width and length (if it's rectangular) or its diameter (for a circular area).
It's possible that the area you want to measure has a strange shape, like an L. In this case, figuring out the total square footage is easier if you divide the area into smaller pieces and figure out each one separately. We'll talk about how to do this a little farther down the page.
After you figure out your square footage, you may want to figure out the volume in cubic yards of materials like mulch or gravel.
How to figure out the area of a rectangle in square feet
Use feet to measure the length and width of the rectangle. The area is then found by multiplying the length by the width. Length (feet) times width (feet) = square feet of rectangle.
Example of how to figure out the square footage of a rectangular room
Let's say we're getting new flooring for our living room and need to measure it. The room is 16 feet long and 12 feet wide, according to our measurements. To find out how many square feet our living room is, we multiply these two numbers: 16 × 12 = 192 square feet. We now know how much flooring we'll need: 192 square feet.
Note: If your measurements aren't in feet, you can first use our length conversion tool to change them to feet.
Workouts for L-shaped rooms and spaces
If you need to figure out how many square feet are in a "L" shape, you can divide it into rectangular sections and treat each one as a separate area. Then you can add up the totals at the end.
We have a step-by-step guide that shows how to measure and figure out square footage.
In the example above, our "L"-shaped room is split into two parts. The first part is 6 feet by 5 feet, which is 30 square feet. The second part is 14 feet by 10 feet, which is 140 square feet. When we add 30 and 140, we get 170 square feet, which is the size of our room.
How to figure out the area of a triangle in square feet
Measure the triangle's length and width in feet.
Add the length and width together to get a number.
Divide your total by two to find the triangle's square footage.
Measure the triangle's length and width in feet.
Add the length and width together to get a number.
Divide your total by two to find the triangle's square footage.
The formula for figuring out a triangle's square footage is length width / 2. If you need to figure out how much materials will cost for a triangle-shaped area, just multiply the number of square feet by the "price per square foot."
In the first example, our triangular area is 16 feet long and 12 feet wide. To figure out how much space there is, we multiply 16 by 12 and then divide by 2. Our calculation: 16 × 12 / 2 = 96 square feet.
How to figure out how many square feet a circle has
Find out how many feet your circle is across.
Cut the diameter in half, and then square it (multiply it by itself).
Add your total amount to (3.14159265)
The formula for figuring out a circle's area is: r2 (with r being the radius of the circle, which is half the diameter). The sign for pi is (3.14159265).
In our previous example, the diameter of our circular area was 16 feet. To find the square footage, we divide our diameter in half, multiply the result by itself, and then multiply it by. Our calculation: π × (16 × / 2)² = 201 square feet.
How to figure out how many square feet a house has
If your house is a perfect rectangle, you can figure out how many square feet it has by measuring its length and width and multiplying the two numbers. This will tell you how much space is on each floor. You can multiply this number by the number of floors in your house if it has more than one.
If your property has a complicated shape, you might want to make a floor plan of each level. Then, you can divide each floor into its own shape and take measurements for each room. Here's a video example...
Quick facts
Statistica says that the average size of a single-family home in the United States is 2,261 square feet.
how many square feet is a 20x20 room?
A room that is 20 feet wide and 20 feet long has a square footage of 400 square feet. To figure this out, multiply the width by the height. 20ft × 20ft = 400 sq ft.
A room that is 20 feet wide and 20 feet long has a square footage of 400 square feet. To figure this out, multiply the width by the height. 20ft × 20ft = 400 sq ft.
How big is a 12x12 room in square feet?
A room that is 12 feet wide and 12 feet long has a square footage of 144 square feet. To figure this out, multiply the width by the height. 12ft × 12ft = 144 sq ft.
A room that is 12 feet wide and 12 feet long has a square footage of 144 square feet. To figure this out, multiply the width by the height. 12ft × 12ft = 144 sq ft.
A rundown of the numbers
Here's a summary of what we've talked about so far.
Here's a summary of what we've talked about so far.
Shape of a room or area
How to Figure Sq. Ft (in feet)
L-shaped width length of a rectangle
Measure each rectangle separately.
L-shaped width length of a rectangle
Measure each rectangle separately.
Triangle
Base length Height / 2 Circle diameter [Diameter / 2]
If you know how many square feet something is and want to figure out how many cubic feet it is, you can use our square feet to cubic feet calculator. Check out our step-by-step guide for more information on how to measure and figure out the square feet of a room or house.
We also have a tool to help you convert between acres and square feet if you need to measure land.