Four Sided Field Size Acres

The Four-Sided Field Size Acre calculator computes the area of a field with four straight sides given the length of the four sides and the length of a diagonal between opposing corners.  

INSTRUCTIONS: Choose units and enter the following:

• (A) Length of side a
• (B) Length of side b
• (C) Length of side c
• (D) Length of side d
• (Dg) Length of the diagonal  (See Diagram)

Acres in a Field (A): The calculator returns the area in acres and square feet.  However, these can be automatically converted to compatible units via the pull-down menu.

The Math / Science

Start in one corner of your field, and measure the length of the four sides (A,B,C,D).  Then from the original corner, measure the diagonal (Dg) to the far corner.  See diagram.  Then enter measurements above. The area of a four sided field calculation breaks the field into two triangles.  That is why the diagonal (Dg) is needed.  The first triangle has sides of A, B and Dg.  The second triangle has side of C, D and Dg.

The formula for the area of a triangle based on the length of the three sides is:

        `A = sqrt((a+b+c)/2((a+b+c)/2-a)((a+b+c)/2-b)((a+b+c)/2-c))`

where:

• A is the area of the triangle
• a is the length of one side
• b is the length of one side
• c is the length of one side

For other area calculators, see the following:

• Area of a Circle - Multiple functions to compute the area of a circle or portions of a circle.
• Area of Triangle -  Three Sides
• Area of Quadrilateral - Four Sides
• Area of Pentagon - Five Sides
• Area of Hexagon - Six Sides
• Area of Heptagon - Seven Sides
• Area of Octagon - Eight Sides
• Area of Nonogon - Nine Sides
• Area of Decagon - Ten Sides
• Area of Hendecagon - Eleven Sides
• Area of Dodecagon - Twelve Sides
• Area of Polygon  -  Any number of sides (n).