How to use this calculator
- Enter Fence height in ft.
- Enter Frost line in in.
- Press Calculate. The highlighted row is your order quantity; the note beneath it translates the number into real-world terms.
Formula & constants
Bury 1/3 of the above-ground height, and always below frost line: hole depth = max(height ÷ 3, frost + 4 in) plus a 4 in gravel base. A 6 ft fence in a 24 in frost zone needs 28 in holes and 9 ft posts. Every default in the fields above is editable — when your supplier’s spec sheet lists a different density, coverage rate or price, enter that number instead. The waste and compaction allowances follow common trade practice; see our methodology page for the derivation of each formula and the standards it references.
Where this fits in the project
Fence runs are linear takeoffs: posts on 8 ft centers, two or three rails per section, then infill. Every post needs a hole below frost line — check the post depth calculator — and about two bags from the concrete bag calculator to set it.
How this connects to your project
No quantity stands alone — each material in the chain depends on the ones around it. These are the planning steps that pair with the fence post depth calculator:
- Fence Calculator — Every fence needs properly set posts.
- Fence Cost Calculator — Post depth affects concrete and labor costs.
- Concrete Bag Calculator — Calculate bags of concrete for post setting.
- Concrete Footing Calculator — Post holes are mini footings.
Frequently asked questions
Why must posts go below frost line?
Freezing soil expands and jacks shallow posts upward a little each winter — fences lean within a few seasons.
Concrete or gravel post setting?
Concrete for gates and high wind; compacted gravel drains better and extends wood post life elsewhere.
Last verified: — prices reflect current national averages. See our methodology.
Estimates are for planning. Material densities, coverage rates and prices vary by region and supplier — confirm final quantities before ordering, and check local code where structural or electrical work is involved.