Gabion fill calculator

Wall volume V = L × H × T (m³) — you fill the whole cage, voids included, so V is the ordering basis. Stone tonnage = V × the in-gabion bulk density of 1.5–1.8 t/m³ (mid 1.6), which is solid-rock density (2.6–2.8) × (1 − void fraction ~0.35–0.40).

Using solid-rock density over-orders stone by ~60% — the exact mistake this tool exists to avoid, because a well-packed gabion is only ~60–65% rock. Denser stone (granite) sits at the top of the band; add ~10% for settlement and overfilling each 300 mm lift proud by 25–50 mm.

Baskets = ceil(wall volume ÷ basket volume). Choose a basket whose thickness matches the wall thickness T — a 2×1×1 m box (2 m³) does not suit a 0.5 m-thick wall even though the volume arithmetic “works”; use a 2×1×0.5 m box (1 m³) instead.

A 10 × 1 × 0.5 m wall = 5 m³ → stone 5 × 1.5–1.8 = 7.5–9.0 t (≈8.0 t at 1.6, ~8.8 t with 10% overfill); baskets = ceil(5 / 1) = 5 of the 2×1×0.5 m size (thickness 0.5 = wall T, so the geometry is valid).

Lacing/spiral wire (~5% of basket weight), internal bracing/connecting wires, geotextile filter fabric behind retaining walls, and foundation bedding are not counted — add them per the manufacturer’s spec. Fill stone should be angular, well graded, 1.5–2× the mesh aperture.