How many fence posts do I need?

You need one more post than the number of panels. For example, a run of 5 panels needs 6 posts. Posts are spaced at the panel width (typically 1830mm / 6ft centres). Include corner and end posts in your count.

How deep should fence posts be?

Fence posts should be buried at least 600mm (2 feet) deep for a 1.8m (6ft) fence. The general rule is one-third of the total post length should be in the ground. Use postcrete or concrete for a solid footing. For soft or clay soil, go deeper.

Do I need gravel boards?

Gravel boards are strongly recommended. They sit between the ground and the fence panel, preventing the panel from touching the soil and rotting prematurely. They are cheaper to replace than full panels. Standard gravel boards are 150mm x 1830mm treated timber.

What height fence can I put up without planning permission?

In the UK, you can erect a fence up to 2 metres (6.5ft) high without planning permission, unless it borders a highway, in which case the maximum is 1 metre. Fences in conservation areas may have additional restrictions. Always check with your local council.

WoodCalcs

Fence Panel Calculator — Panels, Posts & Gravel Boards

Calculate fence panel, post, and gravel board quantities for a boundary fence.

Panel Size

Total Fence Length

Total boundary run to be fenced (panels are 1830mm/6ft wide)

Include gravel boards

Recommended to prevent panel rot

Price per Panel (optional)

Enter your supplier price for a cost estimate

Price per Post (optional)

Enter your supplier price for a cost estimate

How We Calculate This

This calculator determines quantities for a standard panel fence with posts and optional gravel boards.

Calculation method

Panels = ceil(Fence length / Panel width)

Posts = Panels + 1

Gravel boards = Same as panels (one per bay)

Postcrete is estimated at about 2 bags (20kg) per post for a 100mm post in a 200mm-wide, 600mm-deep hole. Each 20kg bag yields roughly 10 litres of concrete (Tarmac Postcrete PDS), so allow more bags for wider or deeper holes and for corner or gate posts. Standard UK panel width is 1830mm (6 feet).

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.