Fence calculator: how many fence panels, pickets and posts do I need?
A practical fence calculator should start with the total fence run, remove gate openings and then convert the remaining length into the actual fence system you plan to install. Numbivo supports both fence panels and individual pickets or boards, so the same calculator can be used for preassembled garden fencing, privacy panels or a site-built timber fence.
In panel mode, panel width is the working bay width. In picket mode, the installed pitch is the picket face width plus the gap. Because real fences include cuts, damaged pieces and layout adjustments, the order quantity is kept separate from the theoretical installed quantity.
Where to get the fence input data
Fence line, gates and separate runs
Measure the actual planned fence line from a site sketch, survey or marked layout. Record every gate opening and separate run rather than estimating the boundary from property area. If corners, slopes or gate positions matter to the final panel count, keep the run lengths separately so you can check each one before ordering.
Panel width, picket pitch and post spacing
Use the installed dimensions from the manufacturer, system drawing or supplier quotation. A nominal panel size is not always the same as the working bay width between posts. For site-built pickets, measure the actual board face and planned clear gap; use the post spacing required by the chosen fence system or project design.
Post holes and concrete yield
Take post embedment, hole diameter and post size from the project detail or fence-system instructions. Use the concrete bag yield printed on the product packaging when you want a bag count. The calculator does not choose a structurally adequate footing size for you.
Fasteners, allowances and prices
Use the fastening schedule for the actual panel or picket system, then enter the package quantity from the box. Material allowance should reflect cuts, damage, spare pieces and the way separate runs round up. Copy prices using the same purchase unit shown by the supplier.
Fence panel calculator with gates and waste allowance
For preassembled fencing, enter the installed width of one panel or bay. Gate openings are subtracted before the calculator divides the run into panels. The base panel count is rounded up because a partial final bay still needs material. The optional allowance is then applied to produce a purchase quantity.
Where manufacturers supply fixed-width systems, use the real installed bay width rather than the nominal product description. Posts, brackets and panel dimensions can change the centre-to-centre distance. If individual runs have different lengths, calculating them separately gives a better cut plan than combining every side into one number.
Fence picket calculator: board width, gap and rails
For a site-built fence, choose individual pickets or boards. The calculator adds picket width and gap to create the installed pitch, then divides the net fence length by that pitch. This answers searches such as how many fence pickets do I need without assuming one standard board width.
Post spacing is entered separately because it controls the number of fence bays and rails rather than the number of pickets. Enter the number of horizontal rails used in each bay; the result multiplies that by the estimated section count.
Fence post calculator: spacing, gates and required post length
Fence posts are estimated from the material system. Panel fencing uses the panel width as the bay spacing. Picket fencing uses the post spacing you enter. Open runs need end posts, and each gate splits the fence line into another run. A closed perimeter does not need the extra pair of outer ends, but gates still create openings that need posts.
This is a quantity estimate, not a structural fence design. Corner posts, brace posts, terminal posts, gate posts, changes in level and unusual loads can require different post types or quantities. Post spacing and embedment should come from the actual fence system, plans and requirements that apply to the site.
Fence post concrete calculator
The post-hole concrete estimate treats each hole as a cylinder. If you enter the width of a square timber post, the calculator subtracts the post volume inside the concrete depth. Set the post width to zero if you want the full cylindrical hole volume instead.
Enter the yield printed on the concrete bag rather than relying on a fixed bag weight. Different products and markets provide different usable volumes. The calculator can also add a visible concrete allowance for irregular holes, spillage and site variation, then rounds the final requirement up to whole bags.
Fence cost calculator for a quick material budget
Add prices for the actual fence system: one panel or picket, one post, one rail, one concrete bag, one fastener pack and one gate. This produces a transparent material subtotal and makes it easier to compare a panel fence with a site-built picket fence.
The estimate intentionally excludes labour, machine hire, excavation, spoil removal, post caps, brackets, hinges, latches, tension wire, mesh fittings, paint, stain, delivery and permits unless they are represented by one of the editable price fields.
Example fence quantities
The table shows how panel width changes the base number of panels for a 20 m net fence run before waste. These are arithmetic examples only; use the installed dimensions of the fence system you are actually buying.
| Installed panel width | 20 m net run | Panels before allowance |
|---|---|---|
| 1.50 m | 20 ÷ 1.50 | 14 |
| 1.80 m | 20 ÷ 1.80 | 12 |
| 2.00 m | 20 ÷ 2.00 | 10 |
| 2.40 m | 20 ÷ 2.40 | 9 |
For students and apprentices: fence material takeoff practice
These exercises practise linear measurement, subtraction of openings, division with rounding, percentage allowance, post spacing, cylinder volume and package rounding. Load the values, calculate the answer yourself and then reveal the worked solution generated from the same engine as the live calculator.
Exercise 1: 24 m panel fence
An open 24 m fence has one 1 m gate. Use 1.8 m panels, 5% material allowance, 1.8 m fence height, 60 cm embedment and 30 cm post holes.
Exercise 2: 18 m picket fence
Use 90 mm pickets with 20 mm gaps, 2 m post spacing, two rails per bay and 10% material allowance. There is no gate.
Exercise 3: 120 ft privacy fence
A 120 ft run has one 4 ft gate. Use 5.5 in pickets, 0.5 in gaps, 8 ft post spacing, 6 ft fence height and 24 in embedment.
Before ordering fence materials or digging post holes
Measure each fence run and mark corners, gates, changes in direction and changes in level. Confirm the actual installed panel width or post spacing, post dimensions, hardware, gate clearances and concrete product yield. Where possible, calculate irregular sides separately so rounding and cut panels are visible rather than hidden in one total length.
Before excavation, check property boundaries, underground services, local fence-height or setback requirements and any approval rules that apply. Wind exposure, soil conditions, frost, retaining conditions and large gates can materially change post and footing requirements. This calculator is for material takeoff, learning and budgeting; it does not certify structural safety or legal compliance.
Learn the estimating method
Go deeper into the method or check reference values without losing the context of this calculation.