Farm Fencing Materials Calculator NZ
This works out what a run of post and wire farm fence actually takes: line posts, strainers, battens, metres of wire and the number of coils that comes to, then prices the lot and gives you a cost per metre. The fencing calculators already on this site are for timber palings around a section, which is a different job with different materials, so this one is built for the paddock fence instead. Two parts of the arithmetic catch people out. The first is that a fence with ten bays has eleven posts, so the count depends on your post spacing far more than on the length, and halving the spacing very nearly doubles the bill. The second is wire: coils are sold by weight, not by length, so how far a 25 kilogram coil goes depends entirely on the gauge. Rather than quote a coil length as though it were a standard, this page works it out from the wire diameter and the density of steel, and lets you type in the length printed on your own coil if it has one. Everything here is a quantity and a price you set, not a rate anyone publishes, so treat the total as a materials estimate to take to a supplier rather than a quote.
| Item | Unit price | Quantity | Cost |
|---|---|---|---|
| Line posts | 97 | $1,164.00 | |
| Strainer posts | 4 | $112.00 | |
| Battens | 300 | $1,050.00 | |
| Wire coils | 7 | $525.00 | |
| Staples, insulators and sundries | 1 | $0.00 |
Materials only. Labour, cartage, gateways and any waterway crossing are on top, and on most farm fencing jobs the labour is the larger half of the bill.
How it works
Bays are the fence length divided by the post spacing, rounded up, and the post count is one more than that because a fence is posted at both ends. Strainers are then taken out of that total and priced separately, since a strainer stands where a line post would otherwise go rather than being an extra post beside it. Battens are the number of bays multiplied by the battens you want in each. Wire is the length multiplied by the number of runs, plus your allowance for tying off, straining and the extra taken up at corners.
Where the coil length comes from
Wire is sold by weight, so the metres in a coil follow from the gauge. A wire of diameter d has a cross section of pi times d squared over four, and steel weighs about 7,850 kilograms per cubic metre, so the mass of a metre of wire is fixed once you know the gauge. Divide the coil weight by that and you have the length. For 2.5 millimetre wire this puts a 25 kilogram coil at roughly 650 metres. It is arithmetic rather than a published standard, and galvanising and manufacturing tolerance both shift it slightly, so if your coil states a length, type it in and the calculator will use that instead.
Worked example
Five hundred metres of conventional fence at 5 metre spacing gives 100 bays and 101 posts, of which 4 are strainers at the ends and corners, leaving 97 line posts. Three battens to a bay is 300 battens. Eight wire runs over 500 metres is 4,000 metres of wire, and a 5 percent allowance for tying off and straining takes it to 4,200 metres, which at roughly 649 metres to a 25 kilogram coil of 2.5 millimetre wire means 7 coils. At $12.00 a post, $28.00 a strainer, $3.50 a batten and $75.00 a coil that is $2,851.00 of materials, or $5.70 a metre before labour.
Related calculators
- Fencing Calculator: timber palings and rails for a section fence.
- Stock Units: what the paddock you are fencing will carry.
- Lifestyle Block Stocking: sizing stock to a small block.
- Stock Water: the other thing a new paddock needs.