Trade & construction Australia
Colorbond Fence Calculator
A Colorbond fence is built from steel sheets slotted between posts and rails, so the quantities follow directly from the fence's length. This calculator counts panels, posts and rails from the length, panel width and gates, with a spare allowance.
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Check your supplier: Colorbond panel widths vary slightly by profile and system.
Panels needed
—Fence length less gates
—
Posts
—
Rails
—
Plinths (if used)
—
Gate width total
—
The working
How many Colorbond panels do I need?
Subtract the gate openings from the fence length, divide by the panel width and round up. At 2.35 m a panel, 24 m of fence with one 1 m gate is 10 panels, with 15 posts including both gate posts and two corners, and two rails per bay.
Before you build
Boundary fences are shared between neighbours, and in most states the law says who pays and how disputes are settled. Check the Dividing Fences or equivalent legislation in your state, and talk to your neighbour. Fence height limits and any restrictions from the council or an estate covenant also apply.
Pool fences are a separate case governed by their own standards.
Posts and footings
Posts are usually concreted in, and the depth depends on the fence height and the system. The footing concrete volume can be found with the concrete calculator. A fence on a slope is stepped, which changes the panel count slightly.
For the concrete for the footings, use the concrete calculator.
How this is calculated
The rule, step by step, so you can check any figure by hand.
fence length less gates = total length − gates × gate widthpanels = length less gates ÷ panel width, rounded up, plus any spareposts = panels + 1 + 2 per gate (a gate has a post each side) + one for each extra cornerrails = panels × rails per bayplinths, one beneath each panel on a sloping or soft base, = panels
Posts are the count that goes wrong. In a straight run there is one more post than panels, and each gate needs a post on both sides, one of which is shared with the neighbouring panel in most systems. Corners add a post each, and the calculator treats them as extra posts so you are not caught short.
Panel width matters because a fence is built to the post spacing, not the sheet width. A 2.35 m panel in a 24 m fence leaves a part-panel at the end that is cut to fit, so the count rounds up.
A worked example
A 24 m boundary with one 1 m gate and two corners, 2.35 m panels.
- Length less the gate23.0 m
- Panels10
- Posts, panels + 1 + gate post + 2 corners15
- Rails, 2 per panel20
10 panels and about 15 posts.
Different systems use different post spacings, so compare the count with your supplier's quote.
Colour and finish
Choose a colour that suits your house and neighbour, and check the finish options and warranty with the supplier. Cut edges and scratches should be touched up to prevent rust.
What it leaves out
Concrete, capping, fixings, gate hardware and installation are not included. Steep slopes, curved boundaries and changes in height need a plan from the supplier.
What this calculator does not do
- Straight runs; steps and curves change the count
- Post spacing follows panel width
- Concrete and fixings are not counted
- Boundary-fence law and height limits vary by state
Common questions
How many Colorbond panels for 20 metres?
At 2.35 m a panel, 9 panels (20 ÷ 2.35 = 8.5 rounded up), more if there are gates.
How many posts do I need?
One more than the panels in a straight run, plus extra for gates and corners.
What height can I build a fence?
Rules vary by council and state. Many allow up to 1.8 m on a side boundary without approval, so check yours.
Who pays for a boundary fence?
State legislation sets who pays and how, and usually expects neighbours to share the cost.
Do I need plinths?
Not always. They are used on slopes or soft ground to keep the base of the panel clear.
Where these numbers come from
- National Construction Code (ABCB) The code that sets minimum building requirements in Australia
- Australian Government — business.gov.au building and construction General information on building licences and approvals
Method last reviewed 2026-10-28 This calculator uses fixed rules rather than rates that change, and its method is re-checked against the sources above at least once a year. Out of date? Tell us and we will fix it.
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