Rip Rap Calculator

ft
ft
in
Construction

Calculate volume and weight of rip rap (armor stone) needed for erosion control.

Formula

Volume (cu yd) = L × W × D(ft) ÷ 27; Tons = cu yd × 1.6
  • Rip rap density varies by stone size and type: 1.4–1.7 short tons/cu yd.
  • Minimum depth: 1.5× the D50 (median stone diameter).
  • Add a geotextile filter fabric beneath rip rap.

50 ft × 15 ft, 18 in deep

Inputs
  • Area Length: 50 ft
  • Area Width: 15 ft
  • Depth: 18 in

50 × 15 × 1.5 = 1125 cu ft ÷ 27 = 41.67 cu yd × 1.6 = 66.7 tons.

Frequently asked questions

What size rip rap should I use?
Small (3–6 in) for light erosion; medium (6–12 in) for moderate slopes; large (12–24 in) for steep slopes or high-flow streams. Consult an engineer for critical applications.