Rip Rap Calculator
Tonnage of rip rap for slopes and shorelines.
Enter your values
ⓘ Live results
Results
- Rip rap needed
- 70 tons
- Layer thickness
- 13.5 in
- Cubic yards
- 50 yd³
- Estimated cost
- $4,200.00
- Filter fabric
- 1,320 sq ft
Quick answer
Rip rap tonnage = area × thickness in feet × 1.4 tons per cubic yard equivalent, with thickness usually 1.5 to 2 times the median stone size.
tons = area × depth/12 ÷ 27 × 1.4
How to use the Rip Rap Calculator
- 1Measure the length and the width of the slope face.
- 2Enter the median stone size class you are buying.
- 3Keep the thickness multiplier at 1.5–2 for most erosion work.
Worked example
Using the values the calculator loads with:
Inputs
- Length along slope100 ft
- Slope width12 ft
- Median stone size9 in
- Thickness × stone size1.5 ×
- Price per ton60 $
Results
- Rip rap needed70 tons
- Layer thickness13.5 in
- Cubic yards50 yd³
- Estimated cost$4,200.00
- Filter fabric1,320 sq ft
Frequently asked questions
How thick should rip rap be?
At least 1.5 times the median stone diameter, so 9-inch stone needs roughly a 14-inch layer.
Do I need fabric under rip rap?
Yes — geotextile filter fabric stops the soil beneath from washing out through the voids.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.