Fence Post Foundation Calculator
Embedment depth for an unconstrained post by the IBC pole formula.
The classic 'bury one-third' folklore roughly matches this math for short fences in firm soil. Wide holes beat deep ones at resisting overturning — diameter enters linearly, but it also caps S₁ growth.
Formula
Fence Post Foundation Calculator is a free fence post depth 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 Fence Post Foundation Calculator
Embedment depth for an unconstrained post by the IBC pole formula. The calculation implements IBC 1807.3: d = A/2·(1+√(1+4.36h/A)), A = 2.34P/(S₁b) (IBC 1807.3.2.1 — embedded posts). The classic 'bury one-third' folklore roughly matches this math for short fences in firm soil. Wide holes beat deep ones at resisting overturning — diameter enters linearly, but it also caps S₁ growth.
How to use Fence Post Foundation Calculator
- 1Enter Lateral load on post in kN (Wind on fence panel ≈ p_z×panel area / posts).
- 2Enter Load height above grade in m.
- 3Enter Hole/footing diameter in mm.
- 4Enter Lateral soil bearing in kPa/m depth (IBC: sand/gravel ~150–200; clay 75–100).
- 5Read Required embedment instantly — no submit button needed.
- 6Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Fence Post Foundation Calculator?
- ✓Implements the standard formula — IBC 1807.3: d = A/2·(1+√(1+4.36h/A)), A = 2.34P/(S₁b)
- ✓Reference cited on-page: IBC 1807.3.2.1 — embedded posts
- ✓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 Fence Post Foundation Calculator use?+
It computes IBC 1807.3: d = A/2·(1+√(1+4.36h/A)), A = 2.34P/(S₁b), per IBC 1807.3.2.1 — embedded posts. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
The classic 'bury one-third' folklore roughly matches this math for short fences in firm soil. Wide holes beat deep ones at resisting overturning — diameter enters linearly, but it also caps S₁ growth.
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 Fence Post Foundation 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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