Mathematics, Statistics & Geometry

Volume of Frustum Calculator

Compute the volume of a truncated conical frustum. Mathematically accounts for slanted walls and differing upper/lower circular radii.

Volume
1,172.861
Calculation StepsBottom Radius (R) = 8, Top Radius (r) = 4, Height (h) = 10 Formula: V = (1/3)πh(R² + Rr + r²) V = (1/3)π(10)(8² + (8)(4) + 4²) = 1172.8613

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The Geometry of Truncated Solids

The Volume of Frustum Calculator specializes in truncated conic geometries. By analyzing the differential between the upper and lower radii, it mathematically accounts for the slanted continuous taper of the container walls.

V=13πh(R2+Rr+r2)\begin{aligned} V = \frac{1}{3} \pi h (R^2 + Rr + r^2) \end{aligned}

Where:
V=
The total 3D cubic space of the truncated cone
h=
The straight vertical distance between the top and bottom circular bases
R=
The radius of the larger, bottom circular base
r=
The radius of the smaller, top circular cut-off base

The Mathematics of Coffee Cups

While "Frustum" sounds like an obscure theoretical shape, it is actually one of the most common geometric objects you interact with daily.

Every time you buy a coffee at a cafe, the paper cup is a perfect inverted conical frustum. The top radius is wide so you can drink, the bottom radius is narrow to fit in a cup holder, and the walls taper uniformly. Manufacturers rely on rigorous frustum calculus to ensure that specific taper yields exactly 16 fluid ounces of volume.

Real-World Applications

  • Manufacturing Design: Calculating the exact liquid volume of household buckets, drinking glasses, and trash cans, which are nearly all designed as frustums so they can "nest" inside each other during shipping.
  • Aerospace: Calculating the volumetric fuel capacity of the flared thrust nozzles at the bottom of orbital rocket engines.
  • Civil Engineering: Calculating the massive cubic volume of earth and rock that must be excavated to dig an open-pit mine, which forms a massive inverted frustum descending into the earth.

Frequently Asked Questions

A frustum is what happens when you take a standard cone (or pyramid) and slice the top tip off perfectly parallel to the base. A standard coffee cup or a lampshade is a perfect example of a conical frustum.

Because the walls are slanted, the radius is constantly shrinking as you go up. The (R² + Rr + r²) part of the formula mathematically averages out this continuous geometric shrinkage.

If R and r are equal, the slanted walls become perfectly straight. The object mathematically stops being a frustum and becomes a perfect Cylinder. The formula collapses perfectly into the cylinder volume formula.

If the top radius (r) shrinks to exactly 0, the flat top becomes a sharp point. The object becomes a perfect Cone, and the formula instantly simplifies into the standard cone volume formula.

No. This specific calculator uses Pi (π) and is explicitly designed for Conical frustums (circular bases). A pyramid frustum (square bases) requires a slightly different algebraic formula.