Trapezoidal Footing Formula – Detailed Explanation with Figure

Calculating the concrete volume of an isolated footing seems like hectic.

We have explained the process (with diagram) step by step using this simple trapezoidal footing formula. Also embedded an easy to use trapezoidal volume calculator. 

Note: For a better view, read this post on landscape view if you are on the mobile device.

How to calculate the concrete quantity of a trapezoidal footing?

An Isolated footing area may be in rectangular or square shape. We have explained the process for both shapes.

First, We have to calculate the below rectangular part separated by the dotted line (refer the diagram), using rectangular area formula.

Don’t forget to check out Basic Surface Area Formulas.

  1. For rectangular, the Area = A x B
  2. For Square, the Area = A(assuming A=B)

Check out different types of Trapezoid Geometry.

Trapezoidal Footing Formula with drawing

Typical Trapezoidal Footing Diagram

Trapezoidal Footing Volume, 

 V = h/3 (A1+A2+√(A1 x A2))

Where, h – Height of trapezoidal (refer the diagram)

A1 – Area of the lower shape

A2 – Area of the upper shape

Trapezoidal Footing Volume – Example Calculation

Let’s take this example and solve,

Calculating Trapezoidal Footing Volume


We know the formula,

Here, we have assumed square footing,

V = h/3 (A1+A2+√(A1 x A2))

{ Where, A1 = 1.6 x 1.6 = 2.56 m; A2 = 0.8 x 0.8 = 0.64 m2 }

= 0.3/3 ( 2.56 + 0.64 + √(2.56 x 0.64))

V = 0.448 m3

We have also created a simple calculator tool. Make use of it.

Trapezoid Footing Volume Calculator – For Square Footing

Trapezoid Footing Volume Calculator – For Rectangular Footing


Got any errors on the calculator? Let us know to fix it.

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Happy Learning  🙂