# How to Calculate Square Footage

## Square Footage Calculator

### What is Square Foot

Square foot is a unit of area measurement equal to a square measuring one foot on all sides. This unit of measurement is mainly used in the United States, Canada, United Kingdom and some other countries. It is commonly used in architecture, real estate and interior space plans. Its symbol is a simple square with a vertical line bisecting it, ⏍

See Formulas.

### Formulas

```Rectangle:

r = wh

Where:
r = square footage of rectangle
w = width or base of the rectangle
h = height of the rectangle```
```Square:

s = a²

Where:
s = square footage of square
a = measurement of one side of the square```
```Circle:

c = πr²

Where:
c = square footage of circle
π = pi or 3.14159265359
r = radius of the circle```
```Trapezoid:

t =  h/2 (b1 + b2)

Where:
t = square footage of trapezoid
h = height of the trapezoid
b1 = bottom width of the trapezoid
b2 = top width of the trapezoid```
```Parallelogram:

p =  bh

Where:
p = square footage of parallelogram
b = base or width of the parallelogram
h = height of the parallelogram```
```Ellipse:

e =  πr1r2

Where:
p = square footage of ellipse
π = pi or 3.14159265359
r1 = radius of the narrowest portion of the ellipse
r2 = radius of the widest portion of the ellipse```