Choose a measured profile over an assumed barrel shape.
Do three barrel diameters prove that its sides follow a parabola?
Use the matching calculator
Use this decision sequence
- Identify the profile model actually established by a drawing or measurements.
- Use the parabolic-barrel tool only when that radius function is applicable.
- For another profile, measure areas at stations and use the station-volume model.
- State that station approximation accuracy depends on spacing and the shape between stations.
Keep the quantities distinct
| Quantity or assumption | How to use it |
|---|---|
| Parabolic radius model | A specific explicit shape assumption. |
| Three measured diameters | Do not uniquely determine an arbitrary profile. |
| Area stations | Describe more of an irregular container but still need an integration assumption. |
Worked comparison
If an illustrative container has equal 2 m diameter at every measured station across 3 m length, the cylinder and parabolic-barrel special case both give 3π = 9.4248 m³. A bulging container may share its end and middle diameters with several different curves yet have different volumes between those stations. Agreement at three points is not proof of the profile.
Check before using the estimate
Do not represent model-based capacity as a verified vessel rating or infer a working fill level.
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.
Related decisions
Keep continuous strip lengths separate from station-to-station measurements
Are repeated strip segments measured over disjoint portions of the same run?
Why the average end areas can misstate a tapered box volume
Do length and width both change along the height?
Weight each measured station interval separately
Why does averaging all offset widths give the wrong strip area?
Measure a component with linearly changing thickness
When is average endpoint thickness a valid volume input?