Truncated Cone Volume Calculator

Truncated Cone (Frustum)

Calculate volume and surface area

Formulas:

Volume: V = (1/3)πh(R² + Rr + r²)

Slant Height: s = √(h² + (R-r)²)

Surface Area: A = π(R+r)s + πR² + πr²

How to Calculate Truncated Cone Volume

Step 1: Measure Top Radius

Measure the radius of the smaller circular top (r).

Why: The top radius determines the upper cross-sectional area. This is crucial for the volume formula.

Step 2: Measure Base Radius

Measure the radius of the larger circular base (R). Confirm R ≥ r.

Why: The base is larger in a frustum. The inequality ensures valid geometry. R = r becomes a cylinder.

Step 3: Measure Height Perpendicular

Measure the perpendicular distance between the top and base (h).

Why: Height must be perpendicular, not along the slant. Slant measurements overestimate height.

Step 4: Calculate Volume and Surface Area

Apply V = (1/3)πh(R² + Rr + r²) and surface area formulas.

Why: The R² + Rr + r² term accounts for both circular areas plus their geometric mean. This comes from calculus integration.

Step 5: Verify and Document

Check that volume is positive and all radii/heights are valid.

Why: Documentation ensures reproducibility. Verification catches input errors before proceeding with design.

Real-World Example

Traffic Cone Dimensions

Scenario: A traffic cone has top radius 0.2m, base radius 0.3m, height 0.6m. What is its volume?
Step 1: Top radius r = 0.2 m
Step 2: Base radius R = 0.3 m; Check: 0.3 ≥ 0.2 ✓
Step 3: Height h = 0.6 m (perpendicular)
Step 4: V = (1/3)π(0.6)(0.3² + 0.3×0.2 + 0.2²) = (1/3)π(0.6)(0.09 + 0.06 + 0.04) = (1/3)π(0.6)(0.19) ≈ 0.1194 m³
Step 5: Volume positive; all measurements valid ✓
Verification: Formula check: 0.19/3 × π × 0.6 ≈ 0.119 m³
Result: Cone volume approximately 0.119 cubic meters or 119 liters
Interpretation: This volume determines how much material (plastic/rubber) is needed to fill the cone or how much liquid it can hold for weight calculations.

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