How to Figure Out Square Feet

Tape measures are one thing you can use to calculate square footage.
••• tape measure image by Alison Bowden from Fotolia.com

To find the square footage of something is the equivalent of asking the area of a two-dimensional shape or surface. Area is a measure of how much space something takes up in two dimensions. Generally, to determine area, you need two measurements: length and width. People use square footage for several reasons including estimating how much carpet or paint to buy or gauging how large their house is.

Rectangle or Square

    Measure one side of the rectangle. As an example, one side measures 4 feet.

    Measure the adjacent side (not the opposite side) of the rectangle or square. In the example, the adjacent side measures 5 feet.

    Multiply one measurement by the other to determine the square footage of the shape. In the example, 4 feet times 5 feet equals 20 feet squared, aka square feet.

Triangle

    Measure the base of the triangle. For example, say the base of a triangle measures 3 feet.

    Measure the height of the triangle, which is the distance from the base to the top point. In our example, the height of the triangle is 5 feet.

    Multiply the base by the height and divide by two to determine the square footage of the triangle. In our example, 5 feet times 3 feet equals 15 square feet, which divided by two equals 7.5 square feet.

Circle

    Measure the diameter of the circle from one side of the circle to the opposite side of the circle. For example, a circle has a diameter of 10 feet.

    Divide the diameter by two to determine the radius. In our example, 10 feet divided by two equals a radius of 5 feet.

    Square the radius. In our example, 5 feet squared equals 25 square feet.

    Multiply the radius squared by pi. In our example, 25 square feet times 3.14 equals 78.5 square feet.

    Things You'll Need

    • Tape measure
    • Calculator (optional)

Related Articles

How to Calculate the Acreage of a Triangle
How to Determine Square Feet Area
How to Find the Missing Side of a Right Triangle
How to Calculate the Diameter of a Circle From a Linear...
How to Calculate Square Feet With Math
How to Find the Area of Triangles & Trapezoids
How to Calculate Volume of a Circular Cylinder
How to Calculate Area From Width & Length
How to Find the Area of a Polygon
How to Calculate Perimeter and Area Ratio
How to Calculate Acreage From Perimeter
How to Calculate Tree Basal Area
How to Calculate a Circular Area
How to Calculate Width
How to Calculate Cubic Inches in a Cylinder
How to Calculate the Square Meters in a Triangle
How to Calculate Diameter to Square Feet
How to Calculate the Volume of Water to Fill a Rectangular...
How to Calculate Volume of a Rectangular Prism
What Is the Difference Between Yards & Feet?