How many fence panels do I need?

1. Panel fence: the formula

A panel fence is the simplest kind to count. Pre-made panels come in a fixed width — commonly 6 ft or 8 ft in the US and Canada, and 1.8 m in the UK, Australia and New Zealand. Each panel slots between two posts. The formula is:

• Panels = fence length ÷ panel width, rounded up
• Posts = panels + 1

The rounding-up rule matters. A 50 ft fence divided by an 8 ft panel is 6.25, which rounds up to 7 panels — you cannot buy a quarter of a panel. The 7th panel will be trimmed to fit the last section. Your post count is 7 + 1 = 8 posts.

If your fence has a gate, treat the gate opening separately. A 4 ft gate opening means 4 ft less of panel fencing to cover, and the gate itself typically needs heavier gate posts — often 4×4 in (90×90 mm) even when the run uses 4×4 posts anyway, because gate posts bear the swinging load.

2. Panel count chart for common fence lengths

Here are the panel and post counts for common fence runs using standard 8 ft (2.4 m) and 6 ft (1.8 m) wide panels.

Always measure your actual fence line — property boundaries are rarely a round number. Order one extra panel per 100 ft run as a buffer against a bad panel or a mis-cut, and buy all panels in one batch so the colour and finish match.

3. Picket fence: posts, rails and pickets

A picket (or board-on-board) fence is built from scratch rather than snapping in pre-made panels. You need three material counts:

• Posts = ceil(fence length ÷ post spacing) + 1. Standard post spacing is 8 ft on-centre in the US and Canada (1.8 m in metric countries). Closer spacing (6 ft) is common for taller or heavier fences.
• Rails = (posts − 1) × rails per bay. Bays are the sections between posts. A fence under 4 ft uses 2 rails per bay; a 5–6 ft privacy fence uses 3 rails per bay.
• Pickets = fence length ÷ (picket width + gap), rounded up. Standard dog-ear pickets are 3.5 in actual width (a nominal 4 in board) and are typically spaced 1.5 in apart for a semi-privacy look, giving 5 in per picket. A 100 ft fence: 1,200 in ÷ 5 in = 240 pickets. In metric: 90 mm pickets + 40 mm gap = 130 mm per picket, so 30,000 mm ÷ 130 mm ≈ 231 pickets.

Add 5–10% to the picket count for waste: pickets get damaged, split or cut to fit corners. Buy them in one delivery so the treatment, colour and dimension all match.

4. A worked example — 150 ft picket fence

You want a 150 ft picket fence, posts at 8 ft on-centre, 3.5 in pickets with a 1.5 in gap, and 3 rails per bay. Here is the calculation:

1. Posts: 150 ft ÷ 8 ft = 18.75, rounded up to 19 bays. Posts = 19 + 1 = 20 posts.
2. Rails: 19 bays × 3 rails = 57 rails.
3. Pickets: 150 ft = 1,800 in. Each picket allots 3.5 + 1.5 = 5 in. 1,800 ÷ 5 = 360 pickets (no rounding needed here). Add 10% for waste = 396, so order 400 pickets.

In metric: a 45 m fence with posts at 1.8 m, 90 mm pickets with a 40 mm gap, 3 rails per bay. Posts = ceil(45 ÷ 1.8) + 1 = 25 + 1 = 26 posts. Bays = 25. Rails = 25 × 3 = 75 rails. Pickets = 45,000 mm ÷ 130 mm = 346.2, rounded up to 347 pickets, plus 10% = about 382 pickets.

The fence calculator runs all of this in one step — switch to picket mode, enter the fence length, post spacing, picket size and gap.

5. Posts: depth, concrete and spacing

This guide and calculator size the panels, pickets, posts and rails — the above-ground material count. They do not tell you how deep to set posts or how much concrete to mix. Post depth depends on:

• Frost depth — in cold climates, posts must go below the frost line to avoid heaving. In Canada, that can be 4–5 ft (1.2–1.5 m) deep.
• Fence height — a 6 ft privacy fence needs a deeper post than a 3 ft picket fence. The general rule of thumb is one-third of the total post length in the ground.
• Soil type — sandy or loose soil needs a wider concrete footing; clay holds differently.

Check post depth requirements with your local building authority (many jurisdictions require a permit for fences over a certain height). Use the concrete calculator to work out how much concrete to mix for each footing once you know the hole size.

6. Gates and corners

Gates and corners both affect the panel and post count. For a gate opening: subtract the gate width from the total fence run before calculating panels. A 100 ft fence with a 4 ft gate leaves 96 ft of fencing = ceil(96 ÷ 8) = 12 panels. Gates typically need their own posts — two gate posts per opening — and those posts are usually larger (4×6 in / 100×150 mm instead of 4×4 in / 90×90 mm) to handle the swing load.

Corner posts are shared between two fence runs but only counted once per corner, so a rectangular yard with four corners still only needs one post at each corner — your post count from the formula already includes them as the end posts of each run. If you are building a return on a run (an L-shape), add the length of both legs and calculate together, but budget one extra post per inside or outside corner to allow for the overlapping runs.

Common questions

How many fence panels do I need?

Divide your total fence run by the panel width and round up. A 100 ft fence using 8 ft wide panels: 100 ÷ 8 = 12.5, rounded up to 13 panels. In metric, a 30 m fence in 1.8 m panels: 30 ÷ 1.8 = 16.7, rounded up to 17 panels. The fence calculator does this instantly.

How many fence posts do I need?

Posts = panels + 1. There is one post at each end plus one between every adjacent pair of panels, so a 13-panel fence needs 14 posts, and a 17-panel fence needs 18 posts. For a picket fence built from scratch, posts = ceil(fence length ÷ post spacing) + 1.

How many pickets do I need for a fence?

Divide the fence length by (picket width + gap) and round up. A 100 ft fence with 3.5 in pickets and a 1.5 in gap allots 5 in per picket, so 1200 in ÷ 5 in = 240 pickets. Add 5–10% for waste.

How many rails do I need for a fence?

Rails = bays × rails per bay, where bays = posts − 1. A fence with 14 posts has 13 bays; at 3 rails per bay that is 39 rails. Standard wood fences use 2 rails for fences under 4 ft and 3 rails for 5–6 ft privacy fences.