Enter your fence run length and post spacing to get the panels, posts, rails and palings you need - Colorbond sheet fencing or a timber paling fence - plus the bags of rapid-set concrete. Add your own prices, or an installed rate per metre, for a cost estimate. Works in metres and millimetres.
Centre-to-centre post spacing - 2.4 m (8 ft) is a common default. Closer spacing makes a stiffer fence; wider needs stronger rails.
Enter the prices you are quoted - leave any blank to skip it. The calculator multiplies each by the quantity above.
Rails
27 · 60.0 m
Palings
220
Bays
9
Post-mix bags
20
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It works for any wood or timber fence - picket, close-board, board-on-board or pre-made panels. A fence run is divided into bays no wider than the post spacing. Each bay is one panel; posts close each bay, rails span them, and pickets or boards clad the run:
bays = ceil(run length ÷ post spacing)
posts = bays + 1
rails = bays × rails per bay
pickets = ceil(run length ÷ (picket width + gap) × wastage)
concrete = posts × bags per post
Bays round up so no gap is ever wider than your spacing - it is the post count people run short on, so the estimate stays on the generous side. Building an L-shaped, three-sided or full perimeter fence? Add a run for each straight length and the quantities pool. When a run starts off the end of the one before it, tick “Starts off the previous run at a corner” and the two runs share that corner post - so it is counted once, not twice. Leave it unticked for a detached run that needs its own posts at both ends. All math runs in exact metric internally, so switching units never changes the answer.
This example follows the unit system you pick in the calculator above.
A 20 m run at 2.4 m post spacing, 3 rails per bay, 90 mm pickets with a 10 mm gap, 10% wastage, 2 bags of post-mix per post:
| Part | Rule of thumb |
|---|---|
| Post spacing | 1.8-3 m (6-10 ft); 2.4 m (8 ft) is the common default |
| Rails per bay | 2 up to 1.2 m, 3 for privacy height, 4 over 1.8 m |
| Post depth | About a third of the above-ground height, in concrete |
| Post-mix | 1-2 bags per standard post; more for tall or exposed posts |
| Picket gap | 0 for close-board/privacy, or the picket width for a classic spaced look |
The calculator builds a fence two ways - pick Construction at the top:
Unlike a stick fence - whose pickets run across the front of the posts, so the post width never affects the length - panels bolt to the side of the posts and sit between them. So each panel + post repeat eats up the panel width plus one post width, and the centre-to-centre post spacing is the panel width plus the post width.
Both modes share the same posts and post-mix concrete maths, and both feed the cost section below - so you can price a DIY steel-panel run by the panel, post, bracket, cap and bag, or take an installed rate per metre.
panels = ceil(run length ÷ (panel width + post width)) (one panel per bay)
posts = panels + 1 per run
brackets = panels × brackets per panel
caps = posts
The materials list above is what sets the price, so this calculator estimates cost from your numbers rather than a national average that drifts out of date. In the Cost estimate section, pick how you are pricing the job:
material cost = posts × $/post + rails × $/rail + pickets × $/picket + bags × $/bag
installed cost = total fence length × installed rate per foot
Leave any price blank to skip it - a partial list still totals, so you can price just the pickets if that is all you need. Cost figures are indicative; set each price to a real quote for your area, and add gates, hardware and any tool hire or waste removal separately.
In Australia, the vertical boards are called palings (commonly 100 × 15 or 75 × 15 mm), fixed to two or three rails on 100 × 100 mm H4-treated posts set in rapid-set concrete.
Go deeper on any part of the job:
A Colorbond fence is a panel fence, so set Construction to Pre-made panels. The number of panels equals the number of bays - the run length divided by the panel width, rounded up. Standard Colorbond panels are 2.4 m wide, so a 20 m run needs ceil(20 ÷ 2.4) = 9 panels and 10 posts. The calculator returns the panels, posts, rails and post caps, plus the concrete per post.
Colorbond posts sit at the panel width, which is 2.4 m for the standard sheet - so the post spacing and the panel width are the same number. Drop to a narrower bay on a windy site or where the fence steps down a slope. Set your panel width above and the calculator spaces the posts to match and counts the closing post.
Divide the run length by the paling width plus any gap, and round up, then add a wastage allowance for culled and cut boards. A 20 m run of 100 mm palings butted together needs about 200 palings before waste. Set your paling width and gap above - lapped and capped fences overlap the boards, so put the overlap in as a negative gap - and the calculator adds the wastage for you.
Use 2 rails for a fence up to about 1.2 m and 3 rails for a 1.8 m paling fence, which is the common boundary height in most Australian councils. The calculator multiplies the bays by the rails per bay and also gives the total linear metres of rail to buy.
A standard fence post takes one to two 20 kg bags of rapid-set concrete per post; heavier corner and gate posts in exposed spots take more. Set the bags per post above - the default of 2 is a safe allowance for a boundary fence - and the calculator multiplies by the post count.
Cost is driven by the material list this calculator produces, so the most accurate estimate uses your own local prices rather than a baked-in average. In the cost section, either enter a price per panel, post and bag of concrete to total the materials, or switch to an installed rate per metre to price a contractor job. The calculator multiplies each price by the quantity it already worked out, so the estimate always matches your exact fence.
In most Australian states the cost of a boundary fence is shared equally between the two neighbours, provided the fence is a "sufficient dividing fence" for the area - the rules and the notice you have to serve differ by state, so check your state fencing act. Work out the full materials cost here, then halve it to see your likely share, and remember that anything above the standard fence (extra height, a better finish) is usually paid for by whoever wants it.
The spacing rules and formula for counting fence posts, panels and bays.
Read guide→The formula and gap rules for counting fence pickets, boards or palings.
Read guide→Estimate the stain or paint for a fence from area, coverage and coats.
Read guide→Estimate fence cost from the material list - posts, panels, concrete and labour.
Read guide→Wood, vinyl, chain link, privacy and picket fences compared, with calculator settings.
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