Riprap Layer Volume and Tonnage

Cubic yards and tons of stone to order for a riprap layer.

Run the calculator

Example

You enter

Plan area of the riprap layer (ft²) 500
Layer thickness (ft, at least 1.5 x D50) 2
Stone unit weight (pcf) 165

You get

Layer volume 37.0 cy
Stone to order 82.5 tons

Details, formula, and sources

volume = area x thickness / 27, tons = area x thickness x unit weight / 2000. A 500 sf outlet apron 2 ft thick is 37 cy and 82.5 tons at solid 165 pcf, but ordering to a placed 130 pcf (voids counted) drops it to 65 tons. The order-quantity companion to riprap-d50.

volume_cy = area_sf x thickness_ft / 27; tons = area_sf x thickness_ft x unit_wt_pcf / 2000.

Layer take-off identity by name (plan area x thickness x unit weight); first-principles volume arithmetic.

The layer take-off is public quantity-survey geometry; the unit weight comes from the stone source.

Estimate. AHJ and licensed professional govern.

Field names used by the API: area_sf, thickness_ft, unit_wt_pcf, volume_cy, tons

Unit weight 165 pcf solid-rock default; order to a placed 120-135 pcf (voids counted)materials practice
Layer thickness at least 1.5 x D50 (from riprap-d50); the plan sets itUSACE riprap practice