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The trapezoidal footing formula is used to determine the volume of a trapezoidal footing from the respective drawing specifications. Here, the trapezoidal footing formula is explained and clarified with the help of an example.Trapezoidal Footing Formula
As shown in figure-1 below, the trapezoidal footing is a combination two components:- Truncated Pyramid
- Rectangular Cuboid

Fig.1. Trapezoidal Footing- Combination of the Rectangular cuboid and Truncated Pyramid
The volume of trapezoidal footing = Sum of (Volume of truncated pyramid + Volume of Rectangular Cuboid)

Fig.2. Plan and Elevation of Trapezoidal Footing


Example - Calculation Using Trapezoidal Footing Formula
The trapezoidal footing formula can be explained with an example. Consider a trapezoidal footing arrangement as shown in figure-3 below.
Fig.2. Example of Plan and Elevation of Trapezoidal Footing
- A1= A x B = 1.5 x 1.5 = 2.25m2
- A2 = a x b = 0.8 x 0.8m = .64m2
- ht = 0.3m