Use the centreline radius when measuring a toroidal ring.
Is the entered major radius the outside edge or the tube centreline?
Use the matching calculator
Use this decision sequence
- Identify the radius of the circular tube cross-section.
- Measure the ring centre to that cross-section’s centreline.
- If starting from an outside radius, subtract the tube radius first.
- Apply the torus model only to a constant circular cross-section around a circular centreline.
Keep the quantities distinct
| Quantity or assumption | How to use it |
|---|---|
| Outside ring radius | Major radius plus tube radius. |
| Inside hole radius | Major radius minus tube radius. |
| Major model radius | Measured to the tube centreline. |
Worked comparison
A ring with an illustrative outside radius 2.5 m and tube radius 0.5 m has major radius 2 m. Its volume is 2π²×2×0.5² = π² m³. Entering the outside 2.5 m as the major radius would produce 25% too much volume. The distinction changes the centreline circumference used to sweep the cross-section.
Check before using the estimate
The tool describes a ring’s geometry, not its pressure capacity, support or safe fabrication.
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.