Measure shaft height separately from a tapered base.
Where does the straight shaft begin in a composite volume?
Use the matching calculator
Use this decision sequence
- Mark the plane where the taper reaches the shaft diameter.
- Measure straight shaft height from that plane to the intended top.
- Record both taper-end diameters and the taper’s perpendicular height.
- Add the two non-overlapping volumes and multiply identical components before order rounding.
Keep the quantities distinct
| Quantity or assumption | How to use it |
|---|---|
| Overall height | Contains both shaft and taper. |
| Straight shaft height | Excludes the taper completely. |
| Taper volume | Uses both end diameters rather than an average diameter squared. |
Worked comparison
An illustrative shaft 1 m in diameter and 2 m above a 1 m-high taper has shaft volume π×0.5²×2 = 1.5708 m³. A taper from 2 m to 1 m diameter adds π×1×(1²+1×0.5+0.5²)/3 = 1.8326 m³. Their total is 3.4034 m³. Using the 3 m overall height as shaft height would count an extra 0.7854 m³.
Check before using the estimate
This reads an existing geometric specification; it does not select a foundation shape or dimensions.
All dimensions, product properties, prices and specifications in this example are illustrative arithmetic inputs. Use the values from your measured plan, selected product data sheet and supplier quote. This guide does not choose construction specifications or certify safety.
Calculation and scope checked 2026-10-04. Methods and scope.
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