Conical frustum area calculator
Calculate surface areas, slant height and volume of a right circular frustum from its radii and height.
Formula
s = √[(r₁−r₂)²+h²]; lateral = π(r₁+r₂)s; total = lateral + π(r₁²+r₂²). V = πh(r₁²+r₁r₂+r₂²)/3.
First radius r₁: 5 cm · Second radius r₂: 2 cm · Perpendicular height h: 4 cm · Lateral area ≈ pi×((5 cm × 0.01 m/cm)+(2 cm × 0.01 m/cm))×(0.05)×10000 · Total area ≈ (109.9557429)+pi×((5 cm × 0.01 m/cm)^2+(2 cm × 0.01 m/cm)^2)×10000 · Slant height ≈ (0.05)×100 · Volume ≈ pi×(4 cm × 0.01 m/cm)×((5 cm × 0.01 m/cm)^2+(5 cm × 0.01 m/cm)×(2 cm × 0.01 m/cm)+(2 cm × 0.01 m/cm)^2)÷3×1000000
How to use
- Enter the two circular radii.
- Enter perpendicular height and choose units.
- Read curved area, total area, slant height and volume.
Examples
- Radii 5 and 2 cm with height 4 cm give slant 5 cm and total area ≈201.06193 cm².
Frequently asked questions
Does total area include both ends?
Yes. Total adds both circular ends; lateral area excludes them.
Which height should I enter?
Use perpendicular height between the parallel circles, not the sloping side.
Can the radii be equal?
Yes. The formula then gives the surface areas of a cylinder.
Sources
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