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Fence Post Calculator
Quick answer: A common rule of thumb buries about one third of a post's above-ground height, so a 6 ft fence needs roughly 2 ft of hole, but many cold-climate areas require going below the local frost line. Enter your height and the frost depth your municipality gives you; the calculator returns post count, hole depth and post length.
How it works
Post count = (length ÷ spacing, rounded up) + 1 + extra corner, end and gate posts. Hole depth is the larger of one third of above-ground height and your entered frost depth plus a margin. Post length = above-ground height + hole depth, rounded up to a common stock length. We do not publish frost depths or code values: they vary by municipality, soil and fence type, so get the number from your building department.
Worked example
Figures below are illustrative examples (2026-10-29), not quotes or guarantees.
Assumptions: 150 ft, 8 ft spacing, 3 extra posts, 6 ft above ground, frost depth left at 0. Result: 23 posts, 24 in holes, 8 ft posts. If your municipality told you 48 in frost depth plus 6 in, the hole becomes 54 in and posts jump to 12 ft. Always call before you dig.
FAQ
4x4 or 6x6?
Gate and corner posts are often upsized; ask your supplier or installer for your wind and soil conditions.
How many concrete bags?
Use the fence concrete calculator.
What spacing?
See fence post spacing.
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