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About the Cone Frustum Calculator
The cone frustum calculator is a free online tool: volume, slant height and surface area. Enter bottom radius (R), top radius (r) and height (h) and the results update instantly, alongside a labelled diagram so you always know which measurement goes where.
Choose your input unit (mm, cm, m, km, in, ft or yd) and optionally show the results in a different one: lengths, areas and volumes are converted correctly. Every answer shows the formula behind it, and the calculation runs in your browser, so nothing is uploaded.
Cone Frustum Calculator example
Bottom radius (R) = 6 cm
Top radius (r) = 3 cm
Height (h) = 8 cmVolume = 527.7876 cm³
Slant height = 8.544 cm
Lateral surface area = 241.576 cm²
Total surface area = 382.9477 cm²
Bottom base area = 113.0973 cm²
Top base area = 28.2743 cm²How to use the Cone Frustum Calculator
- Pick the unit your measurements use. All dimensions must share the same unit.
- Enter bottom radius (R), top radius (r) and height (h). Focus a field to highlight the matching label on the diagram.
- Read the results as you type. The largest card is the main answer; the others are the related measurements.
- Copy a single value, copy everything, or share a link that keeps your inputs.
Cone Frustum Calculator FAQ
What formulas does the cone frustum calculator use?
V = ⅓πh(R² + Rr + r²); l = √(h² + (R − r)²); Lateral SA = π(R + r)l; Total SA = π(R+r)l + πR² + πr².
Can I use different units?
Yes. Pick the input unit and, if you like, a different output unit. Area results are shown in squared units and volumes in cubed units.
Is this cone frustum calculator free and private?
Yes. It is free with no sign-up, and calculations happen on your device, so your numbers are never sent to a server.
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