This square foot calculator determines the square footage of a room, lot, land, property or house no matter the shape. Below the form you can find more on this subject from area formulas for various shapes to some example calculations.

Length: *
Width: *
Edge 1: *
Edge 2: *
Edge 3: *
Top edge: *
Bottom edge: *
Left side: *
Right side: *
Radius: *
Base: *
Height: *
Side: *

How does this square foot calculator work?

This is a useful home tool that you can use whenever you need to compute an area, from when you are about to tile a floor, seed a lawn or to estimate wallpaper amount and started wondering how to calculate square footage.

 The square foot calculator determines the square footage for rectangle, triangle, trapezoid, circle, rhombus and square. All you have to do is select the desired shape, input the values required then the tool will do the work.

How to calculate square footage?

Calculating square footage depends on the shape you have. There is a square footage formula for each standard shape. If the shape you are about to calculate is an irregular one or if it includes few standard geometrical shapes together, then you probably can cut it into a few simple shapes, then calculate their footage separately, then add them together to get the total square foot value.

The form above has 6 tabs, each one being designated to a standard shape, as presented below:


All you need to know is the width and length. If you enter these two details the tool can quickly do the job for you. The square footage formula in case of a rectangle is:

Square footage Rectangle= Length*Width

Ex. 15 feet*10 feet =150 square feet


In this case you need the 3 sides of the triangle. If you input these three details in the form you will get the result, otherwise this is the formula to use:

Square footage Triangle= Square root(S*(S-Edge 1)*(S-Edge 2)*(S-Edge 3)).

Where S=(Edge 1+ Edge 2+Edge 3)/2

Ex. Edge 1= 15ft; Edge 2= 13ft; Edge 3= 17ft; Square footage = 93.90sq. ft.


In this case you need the  top edge, bottom edge, left side, right side. The formula for a trapezoid is:

Square footage Trapezoid= Height* (top edge + bottom edge)/2.


Height= (Square root(s*(s-l1)*(s-l2)*(s-l3)))/l3.

l1=left side

l2=right side

l3=bottom edge – top edge



All you need here is the radius. The sq. ft. formula in case of a circle is:

Square footage Circle= π*Radius*Radius.

Where: π= 3.14159265359.

Ex. Radius= 23ft, Area = 1,661.90 sq. ft.


Square footage Square= Side*Side.


In this case you need its base and height. If you enter these data the Square Foot Calculator can quickly do the job for you. The square footage formula in case of a rhombus is:

Square footage Rhombus= Base*Height.

Ex. Base= 15ft; Height= 23ft Result= 345 sq. ft.

How to convert your results:

If requested, after the calculation you can choose to make the conversion into other units. Below you can find a short list on how to convert the square footage:

1 acre = 43,560 square foot;            

1 square yard = 9 square foot;         

1 square meter = 10.76 square foot;              

1 square inch = 0.00064516 square foot.

25 Mar, 2015