No single standard, and that's the honest answer
There is no one Australian Standard that governs a domestic timber fence the way AS 1684 governs framing. What you actually have to satisfy is a stack of other things: your state's dividing-fences law, your council's height and setback rules, your supplier's specification for the posts and rails, and — if there's a pool anywhere near it — a completely separate and much stricter set of rules.
So this calculator does arithmetic against the spacing you give it, and the rest of this page tells you what to check before you dig.
A worked example
18 metres of 1.8m paling fence, posts at 2.4m, three rails, 100mm palings butted tight, 300mm holes 600mm deep, 5% waste:
- Posts: 18 ÷ 2.4 = 7.5, rounded up to 8 bays, so 9 posts
- Rails: 18 × 3 = 54 m, plus 5% = 56.7 lineal metres — twelve 4.8m rails
- Palings: 18000 ÷ 100 = 180, plus 5% = 189 palings at 1.8m each
- Concrete: π × 0.15² × 0.6 = 0.0424 m³ per hole × 9 = 0.382 m³
- Bags: 0.382 ÷ 0.0093 = 42 bags of 20kg rapid-set
Forty-two bags is 840kg of concrete for an 18 metre fence. Worth knowing before you decide whether it's a two-trip-in-the-ute job or a pallet delivery.
Post spacing and hole depth
2.4 metres is the Australian default for one reason: rails and palings come in lengths that suit it, and a 4.8m rail spans two bays with the join landing on a post. Go wider and the rails start to sag; go narrower and you're buying posts you don't need.
Hole depth runs to about a third of the height above ground, with a practical floor around 450mm:
| Fence height | Hole depth | Post length to buy |
|---|---|---|
| 1.2 m | 450 mm | 1.8 m |
| 1.5 m | 500 mm | 2.1 m |
| 1.8 m | 600 mm | 2.4 m |
| 2.1 m | 700 mm | 3.0 m |
Go deeper and wider for end posts, corner posts and anything hanging a gate — those take the load the rest of the fence doesn't. Add depth again in loose sand, in reactive clay, or on an exposed ridge where the fence is a sail. Crown the concrete above ground level so water runs away from the post rather than sitting against it.
Palings: butted, gapped, lapped, good-neighbour
- Butted — palings side by side. Cover equals the paling width, gap zero. Simplest and cheapest.
- Gapped or slatted — a deliberate 15–25mm gap for airflow and a lighter look. Put the gap in the box — a 20mm gap on a 100mm paling cuts the count by about a sixth.
- Lapped — each paling overlaps its neighbour by 15–20mm so there's no line of sight through the fence as the timber shrinks. Enter the exposed width: a 100mm paling lapped 15mm covers 85mm, which is about 18% more palings.
- Good neighbour / board-on-board — palings alternate front and back so the fence looks the same from both sides. Roughly double the palings, and often heavier rails to carry them.
Talk to the neighbour before you talk to the supplier
A boundary fence is a shared asset, and every state has its own law about who pays for it. In most of them a neighbour is liable for half the cost of a fence that's "sufficient" for the properties, you have to give written notice before you start, and if you want something better than sufficient you pay the difference.
| State / territory | The law that applies |
|---|---|
| NSW | Dividing Fences Act 1991 |
| VIC | Fences Act 1968 |
| QLD | Neighbourhood Disputes (Dividing Fences and Trees) Act 2011 |
| SA | Fences Act 1975 |
| WA | Dividing Fences Act 1961 |
| TAS | Boundary Fences Act 1908 |
| NT | Fences Act 1972 |
| ACT | Common Boundaries Act 1981 |
As the fencer, the practical version: get the notice sorted, in writing, before the posts go in. A fence that gets pulled out because the neighbour never agreed to it is the most expensive kind of rework there is.
Councils have their own say on height — a front fence is commonly capped around 1.2m and a boundary fence around 1.8m before you need approval, with tighter rules on corner blocks, sight lines at driveways and heritage streets. One phone call, five minutes.
Two things that will cost you later
- Treatment level. Anything in the ground wants H4 treated pine as a minimum, and H5 where it's critical or permanently wet. H3 is for above-ground use — put an H3 post in a hole and you'll be back inside a decade.
- Fixings. Hot-dip galvanised as a baseline, stainless within a few kilometres of salt water. The rust streak down a new paling fence starts about six months in.
Pool fences are not this
A swimming pool barrier is a different job with a different rulebook — AS 1926.1, plus state registration and inspection regimes, sets heights, gap limits, gate hardware and non-climbable zones. Don't size a pool fence off a general fencing calculator, including this one.
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How far apart should fence posts be in Australia?
2.4 metres is the standard spacing for a timber paling fence, because rails come in 4.8m lengths that span two bays and join on a post. Tighten it on exposed sites or with heavier infill.
How deep should a fence post hole be?
About a third of the height above ground, with a practical minimum of 450mm. A 1.8m fence gets 600mm; a 2.1m fence gets 700mm. Go deeper for end, corner and gate posts, and in sand or on a windy site.
How many bags of concrete per fence post?
A 300mm wide, 600mm deep hole holds about 0.042 m³, which is roughly five 20kg bags of rapid-set per post. A 250mm hole at the same depth is about 0.029 m³, or a little over three bags.
How many palings do I need?
Fence length divided by the paling cover width, plus waste. An 18 metre butted fence in 100mm palings is 180 palings, or 189 with 5% waste. Lapped palings cover less, so you need about 18% more.
How many rails does a fence need?
Two up to about 1.2m, three for a 1.5 to 1.8m fence, and four once you get to 2.1m and over. Board-on-board fences often want heavier rails because they carry twice the palings.
Does my neighbour have to pay half the fence?
In most states a neighbour is liable for half the cost of a fence that is sufficient for the two properties, and you generally have to give written notice before starting. The law differs by state — check yours, and get it in writing before you dig.
Is there an Australian Standard for a timber fence?
Not one that governs a domestic dividing fence overall. What does apply is your state's dividing-fences law, your council's height rules, and your supplier's specification. Pool barriers are the exception and have their own standard, AS 1926.1.
Other calculators you'll want
General information for Australian trades, and an estimate only — not tax, financial or legal advice. It is not engineering, building or design advice either: a calculator works out a quantity from the figures you enter, and anything that needs sign-off still needs your engineer, certifier or building surveyor. Post spacings, hole depths and rail counts here are common Australian practice, not a standard — confirm them against your supplier's specification and your site conditions. Dividing-fence law, height limits and approval requirements vary by state and council; check both before you build. This is a materials estimate to help you order and quote. Swimming pool barriers are governed separately and are outside what this calculator covers.