Picket Fence Calculator

The traditional UK picket fence gap equals the picket width — typically 70mm pickets with 70mm gaps. For a more closed appearance, reduce the gap to 50mm. For child safety, ensure gaps do not exceed 100mm to prevent small children from getting through. Consistent spacing is key to a professional-looking finish.

Standard UK picket fences are 900mm (3ft) to 1.2m (4ft) tall. Front garden picket fences are typically 900mm-1m. Taller pickets of 1.2m provide more privacy while still maintaining the traditional look. Picket fences over 1m at the front boundary adjacent to a highway may need planning permission.

Use 2 horizontal back rails per bay for picket fences up to 1.2m tall, and 3 rails for fences taller than 1.2m. The top rail should be positioned about 150mm from the picket top, and the bottom rail about 150mm from the bottom. A third rail goes in the centre for taller fences. Use 75×50mm or 75×38mm treated softwood rails fixed to the front of the posts. Note: these are plain rectangular back rails — not triangular arris rails, which are a feather-edge/close-board component.

Use pressure-treated (tanalised) softwood for durability. Pickets are typically 70×19mm or 75×22mm. Posts should be 75×75mm or 100×100mm. Set posts at least one-third of their total length in the ground — and never less than 600mm deep in concrete — going to 750mm or more on exposed or soft sites. For a premium finish, use hardwood such as oak — though this costs significantly more. Always use UC4 treated timber for ground-contact elements.

The formula is: Number of pickets = Total length ÷ (Picket width + Gap width). For example, a 10m fence with 70mm pickets and 70mm gaps: 10,000 ÷ 140 = 71.4, rounded up to 72 pickets. To get even spacing, divide the total length by the number of pickets, then subtract the picket width to find the exact gap.