Rip Rap Calculator

Find the average diameter of rocks to use for your embankment with this rip rap calculator.

Volume to order7.4074 cubic yards200 cu ft · 5.6634 m³

Weight9.9885 US tons9,061.4 kg · 19,976.9 lb · 9.0614 tonnes

MaterialRip rap1,600 kg/m³, about 100 lb/ft³

Cubic feet200

Cubic metres5.6634

In 50 lb bags400if buying bagged rather than bulk

Area covered200 sq ft18.5806 m²

Depth12 in304.8 mm

One cubic yard covers27 sq ftat 12 in deep

The method

volume = area × depth; weight = volume × density

Depth in inches, volume in yards

This is where the arithmetic usually goes wrong. A cubic yard is 27 cubic feet, so spread 4 inches deep it covers 81 square feet — not 27. Divide the depth in inches by 12 before multiplying, or work in a single unit throughout.

Order by volume when you can and treat the weight as a cross-check. Loose densities vary by about 10% between quarries and rise sharply when the material is wet, so a ton of gravel is a less definite quantity than a cubic yard of it.

Add a compaction allowance for anything that will be rolled or tamped. Crusher run and road base typically lose 20–25% of their loose volume once compacted.