Parallel Axis Theorem Calculator
Shift any shape's I to a new axis: I = I₀ + A·d².
The A·d² term usually dwarfs I₀ — in a built-up girder the flange plates' own inertia is trivia; their DISTANCE is the structure.
Formula
Parallel Axis Theorem Calculator is a free parallel axis theorem 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 Parallel Axis Theorem Calculator
Shift any shape's I to a new axis: I = I₀ + A·d². The calculation implements I = I₀ + A·d² (Statics — Steiner's theorem). The A·d² term usually dwarfs I₀ — in a built-up girder the flange plates' own inertia is trivia; their DISTANCE is the structure.
How to use Parallel Axis Theorem Calculator
- 1Enter I about own centroid in cm⁴.
- 2Enter Area A in cm².
- 3Enter Distance between axes d in mm.
- 4Read I about new axis, A·d² transfer term instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Parallel Axis Theorem Calculator?
- ✓Implements the standard formula — I = I₀ + A·d²
- ✓Reference cited on-page: Statics — Steiner's theorem
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Live worked example: the substitution recomputes from your numbers
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Parallel Axis Theorem Calculator use?+
It computes I = I₀ + A·d², per Statics — Steiner's theorem. The formula is displayed under the result along with a worked example substituted with your own inputs.
What should I keep in mind when using this calculator?+
The A·d² term usually dwarfs I₀ — in a built-up girder the flange plates' own inertia is trivia; their DISTANCE is the structure.
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 Parallel Axis Theorem 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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