Fence Panel and Post Quantity Calculator

Summary

Pricing and ordering a panel fence job comes down to one measurement done properly — the total straight-run length, broken at every corner, gate, and change of direction — and then applying a small set of simple ratios to that measurement. Get the run measured and broken into straight sections correctly, and the rest of the takeoff (panels, posts, gravel boards, caps, concrete, fixings) follows mechanically. Get the run measurement wrong, or apply a single "panels = length ÷ 1.83" rule blindly across a boundary with corners and a gate, and the site order is either short (a wasted supplier trip mid-job) or over (surplus stock that's effectively unrecoverable once panels and posts are cut or fixed).

This calculator is the quantity companion to the fencing installation and post-depth articles — it answers "how many of each item do I order for the van", not "what section and depth of post do I need" (that's fence post depth) or "how do I actually install it" (see timber close board fencing and feather edge fencing installation for panel and close-board installation method). It covers straight-run takeoff, corners and gates, gravel boards, post caps and fixings, and concrete quantity, with a full worked example for a typical garden boundary.

Key Facts

• Standard timber fence panel width — 1.83m (6ft), the near-universal UK stock width; some ranges also supply 1.8m panels — check the specific product before calculating
• Post-to-post (bay) spacing — panel width plus post width, typically 1.85m centre-to-centre for a 1.83m panel with 75-100mm posts; do not stretch panels beyond their designed span
• Panels needed — total run length (m) ÷ 1.85m, rounded up to the next whole panel
• Posts needed, straight run — panels + 1 (each bay shares a post with its neighbour, except the two end posts)
• Posts needed, run with internal corners — sum posts for each straight section, then subtract 1 post per internal corner (the corner post is shared between the two adjoining runs, not counted twice)
• Gate posts — priced and ordered separately from line posts; typically a heavier section (100x100mm minimum, often 125x125mm for a driveway gate) set in a larger concrete base to resist the gate's swinging load, and the gate opening itself doesn't take a standard panel
• Gravel boards — one per panel bay (matching the bay's width), used to keep the timber panel clear of ground contact and soil splash-back; count equals the panel count on a standard run
• Post caps — one per post, protects the end grain from water ingress and rot; count equals the post count
• Panel fixing brackets/clips — allow roughly 4 per panel (2 per side, top and bottom) for bracket-fixed panels, or the manufacturer's specified fixing count for slot-in post systems
• Postcrete/rapid-set concrete — allow 2 x 20kg bags per post for a typical 100mm post in a 300mm diameter x 750mm deep hole (see fence post depth for the depth/section rule this is based on); site-mixed concrete needs roughly the equivalent volume in a 1:2:4 mix
• Waste allowance — timber fence panels are not normally cut to fit like guttering, so there's minimal offcut waste on the panels themselves; allow a modest 5% extra on gravel boards and fixings for damage/miscuts, and always order one spare panel on runs over roughly 10 panels in case of transit or handling damage
• Uneven final bay — a real boundary run rarely divides exactly into whole 1.85m bays; rather than leaving an odd narrow final bay, spread the small remainder evenly across all bays on that run (a few centimetres of extra spacing per bay is invisible on site) or plan the fence line to land on a clean multiple where the boundary allows
• Sloping ground — panel fencing on a slope is usually stepped (each panel level, with a gap under filled by a deeper gravel board or infill piece) rather than raked; stepped fencing needs the same panel/post count as a level run of the same measured length, but budget extra gravel board depth or infill timber for the steps
• Planning permission — fences over 2m in height need planning permission anywhere; fences over 1m high on a boundary adjacent to a highway used by vehicles (including its footpath/pavement) also need planning permission, regardless of overall boundary length — a public footpath that isn't an adopted vehicular highway doesn't trigger the 1m limit

Quick Reference Table

Detailed Guidance

Step 1: Measure and break the boundary into straight runs

Walk the boundary and measure it in straight sections, noting exactly where each corner, gate opening, or change of direction falls — the same discipline used for a guttering takeoff (see guttering quantity calculator for the equivalent method applied to eaves runs). A rough sketch with each straight section's length marked is faster and more reliable than trying to hold a complex L-shaped or stepped boundary in your head. Treat each straight section as its own mini-calculation, then combine the results.

Step 2: Calculate panels and posts for a straight run

Formula: Panels = Run length (m) ÷ 1.85m, rounded up. Posts (straight run) = Panels + 1.

The 1.85m figure (rather than the panel's own 1.83m width) allows for the post itself sitting between adjoining panels — using the bare panel width alone under-orders posts on longer runs because it ignores the post's own footprint repeated at every bay junction. On a genuinely long, unbroken run, measure the actual centres you intend to set out on site (adjusting slightly bay-to-bay if the total doesn't divide evenly) rather than treating 1.85m as an unbreakable constant.

Step 3: Handle corners correctly — don't double-count the corner post

For a boundary with one or more internal corners, calculate each straight section as if it were independent, then subtract one post for every internal corner, because the corner post is physically shared between the two adjoining runs and should only be ordered (and its hole dug and concreted) once. A corner does need corner-specific brackets or a post with fixing points on two adjacent faces rather than the standard opposite-face brackets used on a straight run — order these separately, they are not the same fitting as a mid-run post bracket.

Worked example — L-shaped boundary, one corner: Run A = 24m, Run B = 15m, meeting at one internal 90° corner.

• Run A: 24 ÷ 1.85 = 12.97 → 13 panels, 14 posts
• Run B: 15 ÷ 1.85 = 8.1 → 9 panels, 10 posts
• Combined posts before adjustment: 14 + 10 = 24
• Subtract 1 shared corner post: 23 posts total
• Panels: 13 + 9 = 22 panels total (panels aren't shared, only the corner post is)

Step 4: Gate openings

A gate opening is not a panel bay — it needs two dedicated gate posts (typically 100x100mm minimum, often 125x125mm for wider or heavier gates) set in a larger concrete base than a standard line post, because the post has to resist the gate's swinging and racking load rather than just wind load on a fixed panel. Deduct the gate's opening width from the run length before calculating panels for that section, and price the gate posts, hinges, and latch hardware as a separate line — see gate hanging and hardware for the fitting detail.

Step 5: Worked example — full garden boundary takeoff

A typical rear/side garden boundary: 24m rear run (no corners), 1.8m-high close-board style panels, standard timber posts, no gate on this section.

At 1.8m fence height, post section and burial depth follow the 100x100mm / 750mm minimum depth rule from fence post depth — this calculator assumes that sizing has already been confirmed and only covers the item counts above.

Common ordering mistakes

• Using panel width instead of bay spacing. Dividing by 1.83m instead of the post-inclusive 1.85m under-orders posts on a long run, sometimes by a full post over a 30-40m boundary.
• Forgetting to subtract the shared corner post. Treating each straight section as fully independent over-orders one post (and one unnecessary hole and bag of concrete) per corner.
• Ordering gate posts as standard line posts. Gate posts need a heavier section and larger concrete base — under-specifying them leads to a post that racks and fails under the gate's swinging load within a year or two.
• No spare panel on longer runs. A single damaged or split panel discovered on installation day, with the supplier's next available slot a week away, stalls the whole job — one spare panel on runs over roughly 10 panels is cheap insurance.
• Ignoring the uneven final bay. Rather than leaving one obviously narrow bay at the end of a run, spread the small remainder evenly across all bays — a few centimetres per bay is invisible, a half-width final panel is not.

Frequently Asked Questions

What if the boundary doesn't divide evenly into whole panels?

Spread the remainder evenly across all the bays on that run rather than fitting one full-width panels and one narrow offcut at the end. A 24.6m run over 13 bays, for example, works out at roughly 1.89m per bay instead of the nominal 1.85m — a small, invisible adjustment repeated across every bay, rather than one obviously mismatched final panel. Where the difference is larger, consider whether the boundary line itself can be adjusted slightly (with the customer's and, where relevant, the neighbour's agreement) to land on a cleaner multiple.

Do I need extra posts for a taller fence?

Not extra posts in terms of count — the post-per-bay ratio (panels + 1 on a straight run) doesn't change with height. What changes is the post's section size and burial depth: a 1.8m fence needs 100x100mm posts at 750mm minimum depth, while a 2.1m fence needs 125x125mm posts at around 850mm depth — see fence post depth for the full height-to-section-to-depth table, and remember fences over 2m need planning permission.

How much extra concrete should I order for postcrete vs site-mixed?

For postcrete (rapid-set, poured dry then watered), 2 x 20kg bags per post is the standard allowance for a 300mm diameter x 750mm deep hole around a 100mm post — always keep a couple of spare bags on top of the calculated total, since hole sizes vary slightly with ground conditions. For site-mixed concrete (1:2:4 OPC:sharp sand:coarse aggregate), calculate the equivalent volume of the same hole size and order aggregate and cement accordingly, allowing for the volume displaced by the post itself.

Is there a difference in quantity takeoff between panel fencing and close-board (featherboard) fencing?

Yes — this calculator's post-and-panel ratios apply to pre-made panel fencing, where each 1.83m panel is a single fixed unit. Close-board (featherboard) fencing is built up on site from individual feather-edge boards nailed to horizontal arris rails between posts, so the quantity takeoff is different — posts are set at wider centres (commonly 2.4-3.0m) with multiple boards per bay rather than one panel — see timber close board fencing and feather edge fencing installation for that method's specific takeoff.

Regulations & Standards

• The Town and Country Planning (General Permitted Development) Order 2015 (as amended) — governs when a fence needs planning permission; over 2m in height anywhere, or over 1m on a boundary adjacent to a highway.

• BS 1722-5 — specification for close-boarded fences and gates; relevant reference standard for timber close-board construction quality.

• BS 8417 — preservation of timber; governs the Use Class 4 (UC4) pressure treatment required for below-ground post sections.

• Planning Portal — Fences, Gates and Garden Walls — official guidance on planning permission thresholds for fencing.

• BSI — British Standards — BS 1722-5 and BS 8417 standard details.

• TDCA — Timber Decking and Cladding Association — trade body technical guidance relevant to timber fencing materials and treatment.

• fence post depth — post section sizing, burial depth, and concrete base sizing by fence height; this calculator assumes that sizing is already confirmed.

• fence post installation depth — installation detail behind the post depth rule referenced throughout this calculator.

• timber close board fencing — installation method for close-board fencing, which uses a different quantity takeoff to pre-made panels.

• feather edge fencing installation — feather-edge board fitting detail, relevant where close-board rather than panel fencing is being quoted.