Calculator
Example data table
| Scenario | Above-ground | Post diameter | Soil | Exposure | Style | Role | Embedment | Hole depth | Hole diameter |
|---|---|---|---|---|---|---|---|---|---|
| Garden fence end post | 4.0 ft | 4.0 in | Loam | Normal | Solid | End / corner | ≈ 26 in | ≈ 30 in | ≈ 13 in |
| Light trellis line post | 1.2 m | 8 cm | Gravelly | Sheltered | Open | Line post | ≈ 60 cm | ≈ 70 cm | ≈ 24 cm |
Values are illustrative; your site inputs drive the final result.
Formula used
This calculator estimates embedment depth using a practical planning rule, then adjusts it with site-condition multipliers:
Base embedment
base = max( 0.35 × above_ground_height, minimum_embedment, frost_depth )
Adjusted embedment
embedment = base × soil_factor × exposure_factor × fence_factor × role_factor × safety_factor
- Hole depth = embedment + gravel base thickness.
- Hole diameter ≈ 3× post diameter (larger for gate/corner posts).
- Concrete volume uses a cylindrical hole estimate and subtracts post displacement.
How to use this calculator
- Select your unit system and enter above-ground height and post diameter.
- Choose soil type, wind exposure, and your fence/trellis style.
- Set the post role (line, corner, or gate) and an optional safety factor.
- Add frost depth and a minimum embedment if you want a floor value.
- Optional: enable concrete to estimate concrete volume and bag counts.
- Press Calculate. Your results appear above the form, with export buttons.