Field calculator
Fence post and section calculator
Estimating a fence starts with the sections and posts: the run length divided by the post spacing gives the sections, the line posts are the sections plus one, and the rails are the sections times the rails per section. Enter the fence length in feet, the post spacing in feet (6 and 8 are common), and the rails per section. The result covers one straight run, and the most common estimating miss is the extras: every corner, every end, and every gate gets its own post, and gate and corner posts are heavier and set deeper because they take the swing of the gate and the pull of the fence on both sides. Setting depth matters as much as count: line posts go roughly one-third of their length into the ground and below the local frost line, set in concrete for most fence types. And watch the wind, because a solid privacy fence acts like a sail and needs deeper, stronger posts and footings than an open picket or chain-link run of the same height. Use this to size the material order, then confirm the post depth, the spacing, the footing size, and any wind-load requirements with the manufacturer and the local code and AHJ.
Result
Fence post and section count: sections = the run length divided by the post spacing (rounded up), line posts = sections plus one, and rails = sections times the rails per section. Enter the fence length in feet, the post spacing in feet (commonly 6 or 8), and the rails per section. The result covers one straight run; a real fence needs more posts, because every corner, end, and gate gets its own post, and gate and corner posts are heavier and set deeper to take the swing and the pull. Set line posts roughly one-third of their length into the ground and below the local frost line, in concrete for most fence types. Watch the wind load: a solid privacy fence acts like a sail and needs deeper, stronger posts than an open picket or chain-link run. Confirm the post depth, the spacing, the footing size, and the wind requirements with the manufacturer and the local code and AHJ.
anvilfield.com/calculators/fence-post-material-calculator · Free field calculators and FieldOS. A planning estimate, verify against the code, the manufacturer, and the engineer of record.
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Fence post FAQ
How deep should a fence post be?
Set a fence post about one third of its above-grade height into the ground, and always below the local frost line, whichever is deeper. A 6 ft fence usually means a 2 to 3 ft hole, with terminal and gate posts deeper. Add gravel at the bottom and confirm the frost depth your building department uses.
How do you set a fence post in concrete?
Dig the hole about three times the post diameter and below the frost line, add a few inches of gravel, plumb the post on two faces, then pour concrete around it. Crown the top 1 to 2 inches above grade sloping away so water sheds off. Brace it and let the concrete cure before stretching fabric or hanging a gate.
Do automatic gates need safety sensors?
Yes. UL 325 requires automatic gate operators to have entrapment protection, commonly two independent devices per entrapment zone in each direction of travel. Those are photo eyes or contact safety edges that stop and reverse the gate. The gate itself must also meet ASTM F2200 construction rules. Running a powered gate without them is a crush hazard and a liability.
How far apart are fence posts?
Chain-link line posts run up to about 10 ft on center under ASTM F567 practice, and many crews use 8 ft for a stiffer fence. Drop to 6 to 8 ft if privacy slats are added later, because the added wind load overloads posts spaced for an open fence. Ornamental and wood follow the panel or rail length.
Do you need to call 811 before installing a fence?
Yes, and in most states it is legally required. Call 811 a couple of business days before digging post holes so utilities mark gas, electric, water, and communications. Hand-dig inside the tolerance zone around the marks. Hit a line with no locate ticket and you own the repair, which can run into the tens of thousands for fiber.