Gravel Board Calculator — Boards, Clips & Materials

Our gravel board calculator works out the number of boards needed based on either your total fence run length or the number of fence bays. Each bay requires one gravel board.

The formula

Gravel boards = Fence length ÷ Board length (rounded up)
Or simply: Gravel boards = Number of fence bays
Fixings = Boards × 2 (only for mortice concrete posts or concrete boards on timber posts — slotted posts need none)

For example, a 10m fence with 1.83m boards: 10 ÷ 1.83 = 5.46, rounded up to 6 gravel boards. With slotted concrete posts the boards simply slide into the post grooves, so no clips are needed. With mortice (feather-edge) posts, or concrete boards on timber posts, you would add roughly 12 fixings (two per board).

Material comparison

• Concrete gravel boards: 1.83m × 150mm × 50mm, weight approximately 20-25kg each. Rot-proof and maintenance-free. Slot into concrete post grooves
• Timber gravel boards: 1.83m × 150mm × 22mm, pressure-treated softwood. Lighter and easier to handle but will eventually need replacing

Installation tips

• With slotted concrete posts, slide the gravel board into the bottom groove before fitting panels; with mortice posts, fix it with a 2-pin cleat at each end
• Ensure a small gap between the board and the ground for drainage
• On sloping ground, cut timber boards to follow the gradient or stack boards
• Always install gravel boards before fence panels for easiest fitting