How to Measure Fence Length and Count Posts

Fencing estimates go wrong in two places: the measured length and the post count. Length is easy to trace on a map and easy to under-measure, because a plot boundary on a screen is a series of straight segments while a real fence follows the ground. Post count is where the arithmetic bites, because posts are spaced, and a run that divides evenly on paper rarely does on site. A fence length calculator gives you the perimeter; a fence post calculator turns it into posts.

Step one: measure the actual run

• Trace the boundary on a map tool, following the fence line rather than the legal parcel line if they differ.
• Add the gate openings back in before subtracting — a gate needs posts either side, and a gate is not a gap in your post count.
• Add roughly 3–5% for ground contour on uneven land. On steep ground, add more, because the fence follows the slope while the map shows the plan length.

Step two: turn length into posts

For a post-and-rail or stock fence, post spacing is normally 2.4–3.0 m; for a domestic panel fence it is the panel width, usually 1.83 m. Posts = (length ÷ spacing) rounded up, plus one, plus one extra for every corner and every gate hanging post. Then buy a few spares, because broken posts during driving are normal rather than exceptional.

Step three: everything that is not the fence

• Concrete per post: roughly 0.03–0.05 m³ for a line post in firm ground, more in soft ground or for corners.
• Strainers and tensioners on runs over about 50 m, and at every change of direction on wire fences.
• Access: a fence line through a hedge or over a ditch costs time, and time is the largest variable in any quote.

Check the area, not just the length

If the fencing quote is part of a land purchase or a tenancy agreement, the enclosed area matters as much as the run. Measure it with an acreage calculator so the fence, the grass and the rent are all quoted against the same boundary. Where the measured area disagrees sharply with the deed, stop and check the boundary before ordering materials.