Free tool
Fence calculator
A run length in, a materials list out.
A paling fence is four things: posts in the ground, rails between them, palings on the rails, and concrete holding the posts. The counts all follow from the run length and the post spacing.
The sums
Bays are the run length divided by the post spacing, rounded up. Posts are always one more than the bays, because the run has two ends. That off by one is the most common ordering mistake.
Rails are the bay count times the rails per bay, usually two on a 1.5m fence and three on a 1.8m one. Palings are the run length in millimetres divided by the paling width plus whatever gap you are leaving.
Post spacing
Two point four metres between post centres is the usual maximum for a domestic paling fence. Wider and the rails start to sag, particularly in the sun on a long north facing run. Closer spacing costs more posts and less trouble later.
Every corner needs a post, every gate needs two, and a gate post carries a load an ordinary post does not, so it wants to be heavier and set deeper.
Post holes
A 300mm wide hole at 600mm deep is a normal starting point for a 1.8m fence, and it takes about 20 litres of concrete a hole, so a 20 post fence is about 0.4 of a cubic metre. That is right at the line where bagged premix stops being sensible. The concrete calculator will do the volume.
Corner and gate posts go deeper. Sandy or reactive soil changes the answer, and so does a fence acting as a pool barrier, which has its own rules in both states and is not a job to eyeball.
Dividing fences and the neighbour
A fence on a boundary between two properties is a dividing fence, and both New South Wales and Victoria have legislation covering how the cost is shared and what notice has to be given before work starts. In broad terms the cost of a sufficient dividing fence is shared, and anything above that standard is at the cost of whoever wants it.
The practical version: talk to the neighbour and agree in writing before you order materials, not after. Getting that wrong is the single most common way a straightforward fence becomes a tribunal matter. Both states publish the process, and a fencing contractor who works the area will have been through it many times.
On the border
Albury and Wodonga are covered by different fencing legislation, which is worth knowing if you own on one side and live on the other. The border check tells you which state a given address falls in.
Common questions
How many fence posts do I need?
Divide the run length by the post spacing, round up, and add one. A 20m fence at 2.4m spacing is 9 bays and therefore 10 posts. Add a post for every corner and two for every gate.
How far apart should fence posts be?
2.4m between centres is the usual maximum for a domestic timber paling fence. Going wider lets the rails sag, especially on long sunny runs. Closer spacing costs more posts and causes fewer problems.
How deep should a fence post go?
Around 600mm deep in a 300mm wide hole is a normal starting point for a 1.8m fence. Corner posts, gate posts and anything in sandy or reactive soil go deeper. A pool barrier fence has its own requirements in both states.
How much concrete per fence post?
About 20 litres for a 300mm by 600mm hole, so roughly 0.02 of a cubic metre per post. Twenty posts comes to about 0.4 of a cubic metre, which is right at the point where bagged premix stops being practical.
Does my neighbour have to pay half the fence?
Both New South Wales and Victoria have dividing fence legislation covering cost sharing and the notice that has to be given before work starts. In broad terms the cost of a sufficient dividing fence is shared and anything beyond that standard is at the cost of whoever wants it. Agree it in writing before ordering materials.