These fence planning FAQs explain the measurements behind the calculators and the checks that still belong to your local installer. The answers distinguish geometry, ordering allowances and published product guidance from the assumptions used for preliminary planning.
15 questions
Frequently Asked Questions
Depth and frost
How deep should a fence post be?
The depth calculator starts at one-third of above-ground height for normal wind and firm ground. Its selected wind, soil and special-load conditions can use one-half instead. These are planning methods, not engineered footing designs.
Does freezing automatically select the one-half method?
No. Ordinary winter categories do not change the structural fraction. A numerical frost reference can increase final buried depth through the maximum of the structural starting depth and frost reference.
What does Extreme seasonal freezing mean?
It uses an 80-inch preliminary frost reference unless you enter a known local value. This is a generalized planning assumption. Verify local frost depth and obtain qualified installation advice.
What happens when winter conditions are blank?
The structural estimate still calculates. Frost is marked not assessed until a winter category or numerical local reference is supplied.
Does gravel count as buried post length?
No. With the post resting on the base, 24 inches of buried post plus 6 inches of gravel requires a 30-inch hole. The gravel is separate from the post.
How wide should a post hole be?
The depth tool can suggest a practical diameter using approximately three times post width as a preliminary reference for conventional installations.
Concrete and gravel
Are concrete and cement the same thing?
No. Cement binds the other ingredients in concrete. The bag table uses mixed-concrete volume yields, so cement-only bags are not a substitute.
Why subtract the post from concrete volume?
The post occupies space inside the fill. Subtracting that displacement estimates the concrete around it rather than filling the same space twice.
Why might different bag sizes cost different amounts?
Whole-bag rounding, volume yield and unit price all affect the purchase total. The example prices can also represent different mix types; check the exact product before buying.
Is a 10% allowance mandatory?
No. It is an optional ordering allowance. Irregular holes and handling losses vary, so use the allowance appropriate to your actual job.
Layout, materials and costs
Should I space posts six or eight feet apart?
Use the spacing permitted by the fence system. Panel dimensions, connections, terrain and loading can change the suitable layout.
Can I use nominal timber dimensions?
Use measured dimensions for board coverage, physical fit and concrete displacement. A nominal label may differ from the actual face width.
Does the material calculator support vinyl and wire?
Yes. Its eleven styles include board-built, panel, rail, wire and mesh assemblies. Complete kits and loose components use different quantity rules.
Are country prices live quotes?
No. The cost page uses dated country-specific examples where available and accepts supplier overrides. Rest of the World uses the disclosed US baseline.
Can these tools size a gate or wind-loaded foundation?
They estimate quantities; gate loads, soil capacity and wind resistance need specifications or qualified design beyond this calculator.
Sources & References
Method notes · Checked 10 November 2026
Published references
- QUIKRETE: Setting Posts in Concrete. Published guidance for a particular conventional post-setting method: roughly three times post width, height-based depth and a separate gravel base. It is not a universal footing specification.
- QUIKRETE: Concrete Mix technical data. Published approximate mixed yields for 40, 50, 60 and 80 lb concrete bags: 0.30, 0.375, 0.45 and 0.60 ft³. Product labels take precedence.
- USDA NRCS: Fence conservation practice standard 382. The national standard directs users to local Field Office Technical Guide documents for actual planning, design and installation.
- Chain Link Fence Manufacturers Institute: Technical information. Industry technical guidance for chain-link applications. Quantity arithmetic does not verify wind resistance or structural member sizes.
Our calculation and planning assumptions
The 80-inch extreme-freezing reference and automated fraction selection are generalized planning assumptions. No universal standard specifies those winter categories. A known local frost value takes precedence.
Results are preliminary planning estimates. Confirm the actual fence system, local requirements and installation conditions before construction.