Expert Guide
Concrete Calculators
Trapezoidal Footing Calculator – Sloped Foundation
Quality Inspector
Calculate the total concrete volume for sloped foundations (trapezoidal footings) by defining base dimensions, top dimensions, and heights.
📐 Formula & Method
The volume is split into two parts: 1) Rectangular base (L × W × H1) and 2) Trapezoidal frustum (H2/3 × [A1 + A2 + √(A1 × A2)]). The geometry remains consistent for Center, Edge, and Corner footings if parallel areas are used.
Base Volume = L × W × H1
Slope Volume = (H2 / 3) × ( (L×W) + (l×w) + √((L×W) × (l×w)) )
📋 Worked Example
For 1.5m × 1.5m base (0.3m H1), 0.3m × 0.3m top (0.6m H2): • Base Vol = 1.5 × 1.5 × 0.3 = 0.675 m³ • Slope Vol = (0.6/3) × (2.25 + 0.09 + √(2.25 × 0.09)) = 0.2 × (2.34 + 0.45) = 0.558 m³ • Total = 1.233 m³
❓ Frequently Asked Questions
It is a sloped foundation footing that reduces its size from a wide base to the column size, saving concrete while maintaining strength.
No, the total volume for a same-sized frustum remains the same whether the top is centered (Center), on one edge (Edge), or at a corner (Corner).
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