Circular Section Properties Calculator
I, S, J and area for solid round bars and shafts.
J = 2I for circles — the only shape where torsional stiffness comes free. d⁴ scaling: a 10% fatter shaft is 46% stiffer.
Formula
Circular Section Properties Calculator is a free circular section properties for structural engineers, fabricators and site engineers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Circular Section Properties Calculator
I, S, J and area for solid round bars and shafts. The calculation implements I = πd⁴/64; S = πd³/32; J = πd⁴/32 (Shigley's Mechanical Engineering Design). J = 2I for circles — the only shape where torsional stiffness comes free. d⁴ scaling: a 10% fatter shaft is 46% stiffer.
How to use Circular Section Properties Calculator
- 1Enter Diameter in mm.
- 2Read I (bending), S (bending), J (torsion) instantly — no submit button needed.
- 3Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Circular Section Properties Calculator?
- ✓Implements the standard formula — I = πd⁴/64; S = πd³/32; J = πd⁴/32
- ✓Reference cited on-page: Shigley's Mechanical Engineering Design
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Circular Section Properties Calculator use?+
It computes I = πd⁴/64; S = πd³/32; J = πd⁴/32, per Shigley's Mechanical Engineering Design. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
J = 2I for circles — the only shape where torsional stiffness comes free. d⁴ scaling: a 10% fatter shaft is 46% stiffer.
Can I use this for real structural design?+
It implements the exact textbook/code formula cited below the result and is ideal for sizing, checking and learning. Final designs should be verified by a qualified engineer against the full code with all load cases.
Is the Circular Section Properties Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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