Square Footage Calculator
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How it works
Square footage is area expressed in square feet. To calculate a rectangular area, measure the length and width then multiply those two numbers together.
Formula: Area = Length × Width
If you have an oddly shaped area, split it into square or rectangular sections, calculate each area separately, then add them together for the total.
For cost calculation: Total Cost = Area × Price per unit
Square Footage Formulas and Images for Different Areas
Calculate square footage for a square area
Using measurements in feet:
Area (ft2) = Side Length x Side Length
Calculate square footage for a rectangle area
Using measurements in feet:
Area (ft2) = Length x Width
Calculate square footage for a rectangle border area
Using measurements in feet:
Inner Area (ft2) = Length x Width
Total Area (ft2) = (Length + (2 x Border Width)) x (Width + (2 x Border Width))
Area (ft2) = Total Area – Inner Area
Calculate square footage for a circle area
Using measurements in feet:
Area (ft2) = Pi x (Diameter/2)^2
Pi = 3.14
Calculate square footage for a circle border area
Using measurements in feet:
Outer Diameter = Inner Diameter + (2 x Border Width)
Outer Area (ft2)
= Pi x (Outer Diameter/2)^2
Inner Area (ft2)
= Pi x (Inner Diameter/2)^2
Area (ft2) = Outer Area – Inner Area
Pi = 3.14
Obviously, the Circle Border and Annulus are the same, just measured differently.
Calculate square footage for a annulus area
Using measurements in feet:
Outer Area (ft2)
= Pi x (Outer Diameter/2)^2
Inner Area (ft2)
= Pi x (Inner Diameter/2)^2
Area (ft2) = Outer Area – Inner Area
Pi = 3.14
Obviously, the Circle Border and Annulus are the same, just measured differently.
Calculate square footage for a triangle area
Using measurements in feet:
Area (ft2) = (1/4) x square root[ (a+b+c) x (b+c-a) x (c+a-b) x (a+b-c) ]
Calculate square footage for a trapezoid area
Using measurements in feet:
Area (ft2) = ((a + b) / 2 )h