How to Calculate Fence Palings
The standard method for counting fence palings is to divide the fence length by the centre-to-centre spacing of each paling. The centre-to-centre spacing is simply the paling width plus the gap between palings.
Formula: Base palings = ceil(fence length (mm) / (paling width (mm) + gap (mm)))
For example, a 20-metre fence with 75 mm palings and a 5 mm gap:
- Centre-to-centre spacing: 75 + 5 = 80 mm
- Base palings: ceil(20,000 / 80) = 250 palings
- With 10% wastage: ceil(250 x 1.10) = 275 palings to buy
Standard Paling Sizes in New Zealand
| Paling Width | Common Use | Palings per 10 m (5 mm gap) |
|---|
| 70 mm | Narrow tight-fitting fences | 134 |
| 75 mm | Standard NZ paling fence | 125 |
| 90 mm | Wide privacy fencing | 106 |
| 100 mm | Decorative or wide-gap styles | 96 |
| 150 mm | Broadboard ranch-style | 65 |
Palings are most commonly sold in 1.8 m lengths (matching the standard fence height) or in longer lengths that are cut to size on site. Treated pine (H3 or H4 treated) is the standard choice for NZ outdoor fencing. H4 treatment is required for any timber in ground contact (posts); H3 is sufficient for palings above ground.
Rails
Horizontal rails span between posts and carry the palings. The number of rails depends on fence height:
- 2 rails: Fences up to 1.8 m. Top rail and bottom rail, typically set 150 to 200 mm from each end of the paling.
- 3 rails: Fences from 1.8 m to 2.1 m, or any fence in an exposed or high-wind location.
- 4 rails: Fences over 2.1 m or security fencing requiring extra rigidity.
Rails are typically 100x50 mm H4-treated timber. Total rail timber needed equals the fence length multiplied by the number of rails. Add 10% for joins, cutting, and waste.
Wastage and Overbuying
Always buy more palings than the base calculation suggests. Palings can be cracked, warped, or cut short during installation. A 10% wastage allowance is standard for a simple straight run. Allow 15% if there are corners, angles, or openings to cut around, and 20% for complex layouts with multiple gates, pillars, or angled sections.
Posts
This calculator focuses on palings and rails. Posts are typically spaced at 1.8 m to 2.4 m centres depending on the fence style and ground conditions. Number of posts = ceil(fence length / post spacing) + 1. For a 20-metre fence at 1.8 m post spacing: ceil(20 / 1.8) + 1 = 12 posts.
Worked Example
A 20-metre privacy fence, 1.8 m high, using 75 mm palings with a 5 mm gap, 2 rails, and 10% wastage:
- Centre-to-centre spacing: 75 + 5 = 80 mm
- Base palings: ceil(20,000 / 80) = 250
- Wastage (10%): 25 extra palings
- Palings to buy: 275
- Total paling timber: 275 x 1.8 m = 495 lineal metres
- Total rail timber: 20 m x 2 rails = 40 lineal metres
- Grand total timber: 535 lineal metres
Related Calculators
Method: Centre-to-centre spacing method. Palings = ceil(fence length / (paling width + gap)). Wastage applied to paling count before rounding. Rail timber = fence length x number of rails. Total paling timber = palings (with wastage) x fence height.
This calculator gives an estimated quantity based on the dimensions you enter. Actual requirements may vary depending on site conditions, paling straightness, post spacing, and the specific fence style. Always check with your timber supplier and consider ordering a few extra palings to allow for any site surprises.
