Fence Material Calculator — Timber & Concrete Quantities
Get a complete material take-off for a timber fence: enter the run length, fence height, post spacing, picket size and post hole dimensions to see how many lineal meters of posts, rails and pickets to order — and how many 25 kg bags of concrete to buy.
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One 25 kg bag sets approx. 0.012 m³ of concrete when mixed
- 1
Number of bays
⌈30 ÷ 2.4⌉ = 13 - 2
Number of posts
13 + 1 = 14 - 3
Hole volume per post
π × (0.15)² × 0.6 = 0.0424Cylinder: π × radius² × depth (metres). - 4
Total concrete volume
14 × 0.0424 = 0.5938 - 5
Concrete bags (25 kg)
⌈0.5938 ÷ 0.012⌉ = 50
How does this calculator work?
Post lineal meters = (fence height + bury depth) × posts × (1 + waste%). Rail lineal meters = rails × spacing × (1 + waste%). Picket lineal meters = pickets × height × (1 + waste%). Concrete bags = ⌈posts × π × (holeDia/2)² × depth ÷ 0.012⌉. A 10% waste factor covers cutting offcuts on straight fences.
Formula
How this is calculated
Material take-offs for timber fencing work in lineal meters — the total length of straight timber pieces at a given cross-section. Posts need to be long enough for the visible fence height above ground plus the bury depth below; total post lineal meters is that full length times the number of posts, scaled by the waste factor. Rails span each bay (post spacing), and the calculator uses 2 rails per section for fences up to 1.2 m and 3 for taller fences to keep panels rigid. Picket lineal meters is the picket count times the fence height, which converts directly to board quantity from your timber supplier.
Concrete for post footings is calculated from hole geometry: hole volume = π × (diameter/2)² × depth, multiplied by the post count. A standard 25 kg pre-mix bag yields roughly 0.012 m³ of mixed concrete — the calculator divides total hole volume by that yield and rounds up to give bags to buy. Concrete is counted exactly (rounded up), with no additional waste percentage, since unmixed bags keep indefinitely.
The waste factor adds a percentage to every timber quantity (posts, rails, pickets) to account for cutting to length, offcuts, and damaged pieces. Ten percent is typical for a straight fence; allow 15% or more on hilly or irregular layouts.
Frequently asked questions
Timber suppliers sell by linear length: a "meter of 100×100 post" or a "2.4 m rail". Converting counts to lineal meters lets you read off how many standard-length boards to buy and plan for offcuts — you then divide by your preferred stock length (e.g. 2.4 m, 3.0 m) to get the number of pieces.
A 25 kg pre-mix bag typically yields 0.012–0.013 m³ of wet concrete (about 12 litres). Larger 40 kg bags yield around 0.02 m³. To use 40 kg bags, multiply the bag count by 0.012 ÷ 0.02 = 0.6.
No. The waste factor is applied only to timber (posts, rails, pickets). Concrete bag counts are rounded up to the next whole bag as a natural buffer, so no extra percentage is needed.
Also known as
TG we-Calculate Editorial Team. (2026). Fence Material Calculator — Timber & Concrete Quantities [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/fence-material-calculator
TG we-Calculate Editorial Team. "Fence Material Calculator — Timber & Concrete Quantities." TG we-Calculate. 2026. https://we-calculate.com/calculator/fence-material-calculator.
TG we-Calculate Editorial Team, "Fence Material Calculator — Timber & Concrete Quantities," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/fence-material-calculator
@misc{wecalculate_fence_material_calculator, title = {Fence Material Calculator — Timber & Concrete Quantities}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/fence-material-calculator}}, year = {2026}, note = {TG we-Calculate} }
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