Gabion Wall Calculator — Baskets, Stone & Membrane

A standard 1m×1m×1m gabion basket holds 1 m³ of stone, which weighs roughly 1.6-1.9 tonnes depending on stone type (rounded cobbles ~1.8-1.9t/m³, angular granite stone ~1.6t/m³, limestone ~1.7t/m³, recycled concrete ~1.6t/m³). These are bulk densities that already allow for the voids between stones, so suppliers sell — and our calculator orders — by the tonne. If you instead buy loose stone by volume, allow roughly 1.3-1.4 m³ of loose stone per 1 m³ of basket (void ratio ~30-35%). Confirm the exact figure with your chosen supplier and add about 10% wastage.

The most common fill stone size for gabion baskets is 100-200mm cobbles or rubble. The stone must be larger than the mesh aperture (typically 75-100mm) to prevent it falling through. Using stone in the 100-200mm range provides a good balance of visual appearance, structural performance and ease of filling. For facing stones, select the flattest pieces for a neater finish.

For walls up to 1m high on stable ground, a gabion wall can sit on a compacted sub-base of Type 1 aggregate (100-150mm deep) — use our Type 1 Sub-Base Calculator for quantities. For walls over 1m, a concrete strip foundation may be needed. Always place geotextile membrane behind and beneath the wall to prevent soil migration. For sloping sites or walls over 1.5m, seek structural engineering advice.

Gabion walls made with galfan or PVC-coated wire mesh can last 50-100 years. Standard galvanised mesh gabions typically last 30-50 years. The stone fill lasts indefinitely. Gabion walls are increasingly popular in UK gardens as they are permeable (reducing drainage issues), low-maintenance, and can be filled with local stone for a natural look.

Gabion retaining walls under 1m high generally don't need planning permission. Walls that retain a highway or are adjacent to a highway may need permission regardless of height. For gabion walls over 1m high acting as retaining walls, you should seek building control advice as they may require structural calculations. Check our Retaining Wall Calculator for alternatives.