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How to Calculate Fence Panels, Posts and Materials
Building a fence starts with accurate measurements. Ordering too few panels means a second trip to the supplier; ordering too many wastes money. This guide walks you through the formulas and gives you the reference tables you need to get your materials list right first time.
The Panels-Needed Formula
The calculation is straightforward:
Panels needed = Total fence length (m) / Panel width (m), rounded up
For standard 1.83m (6ft) panels along a 15m boundary:
15 / 1.83 = 8.2 → 9 panels
Always round up. A partial panel gap still needs a full panel. If the remainder is very small (under 0.3m), you can trim a panel to fit, but you still need to buy it.
Standard Fence Panel Sizes
| Panel Width | Panel Height | Common Name | Typical Use |
|---|---|---|---|
| 1.83m (6ft) | 0.9m (3ft) | 6x3 panel | Front garden, decorative boundary |
| 1.83m (6ft) | 1.2m (4ft) | 6x4 panel | Side boundary, pet containment |
| 1.83m (6ft) | 1.5m (5ft) | 6x5 panel | General boundary, moderate privacy |
| 1.83m (6ft) | 1.8m (6ft) | 6x6 panel | Full privacy, rear garden |
The 1.83m x 1.8m panel is the most popular choice for rear garden boundaries across Europe. Check local planning regulations — some areas restrict fence height to 2m (including any trellis extension) without planning permission.
Post Spacing Guide
| Panel Width | Post Spacing (centre to centre) | Post Size | Post Length (for 1.8m fence) |
|---|---|---|---|
| 1.83m | 1.83m | 75mm x 75mm | 2.4m |
| 1.8m (metric) | 1.8m | 75mm x 75mm | 2.4m |
| 2.4m (ranch style) | 2.4m | 100mm x 100mm | 2.7m |
| 3.0m (post and rail) | 3.0m | 100mm x 100mm | 2.7m |
The post spacing must match the panel width exactly. Posts that are too far apart leave gaps; posts too close together mean panels will not fit without trimming.
Post Depth Recommendations
| Fence Height | Minimum Post Depth | Recommended Post Depth (exposed site) | Total Post Length |
|---|---|---|---|
| 0.9m (3ft) | 450mm | 500mm | 1.5m |
| 1.2m (4ft) | 500mm | 600mm | 1.8m |
| 1.5m (5ft) | 550mm | 650mm | 2.1m |
| 1.8m (6ft) | 600mm | 750mm | 2.4m |
The one-third rule is a reliable minimum: bury at least one-third of the total post length. Wind loading increases dramatically with fence height, so taller fences in exposed positions should use deeper posts and more concrete. Use our concrete calculator to work out the exact volume if you are mixing standard concrete instead of using Postcrete bags.
Fence Types at a Glance
| Fence Type | Privacy Level | Wind Resistance | Typical Cost per Panel | Lifespan |
|---|---|---|---|---|
| Lap panel | High | Low — catches wind like a sail | EUR 20-35 | 8-15 years |
| Closeboard | High | Moderate — individual boards flex | EUR 40-70 | 15-25 years |
| Picket | Low | High — gaps let wind through | EUR 25-45 | 10-20 years |
| Hit-and-miss | Moderate | High — alternating boards deflect wind | EUR 35-55 | 15-20 years |
| Trellis | None | Very high | EUR 15-30 | 8-12 years |
Closeboard fencing is the most durable option and allows individual boards to be replaced without removing the entire panel. Lap panels are cheaper but tend to blow out in strong winds because the solid face acts as a sail. Building a deck at the same time? Our decking calculator covers boards, joists, and screws for the perfect garden combo.
Complete Materials Checklist
For a 10m fence with 1.83m x 1.8m lap panels:
- Panels: 6 (10 / 1.83 = 5.46, rounded up)
- Posts: 7 (panels + 1)
- Postcrete: 7 bags (1 per post)
- Gravel boards: 6 (one per panel, protects the base from rot)
- Panel clips or nails: 12 pairs (2 per panel)
- Post caps: 7 (keeps rain out of the end grain)
- String line: 1 (keeps posts aligned during installation)
Always buy 10% extra timber to account for defective boards and site adjustments. Having spares on-site saves time and avoids delays. To protect your new fence from the elements, check our exterior paint calculator for fence paint and stain estimates.
These calculations are estimates only. Actual requirements may vary depending on surface conditions, product specifications, and installation methods. Always consult a qualified professional for precise measurements.
Prices updated: 2026-03Frequently Asked Questions
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