Rip Rap Calculator
Tonnage of rip rap for slopes and shorelines.
Enter your values
Results update instantly as you type — no submit needed.
Results
- Rip rap needed
- 70 tons
- Layer thickness
- 13.5 in
- Cubic yards
- 50 yd³
- Estimated cost
- $4,200.00
- Filter fabric
- 1,320 sq ft
Quick answer
Rip rap tonnage = area × thickness in feet × 1.4 tons per cubic yard equivalent, with thickness usually 1.5 to 2 times the median stone size.
tons = area × depth/12 ÷ 27 × 1.4
At a glance
| What it does | Tonnage of rip rap for slopes and shorelines. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Length along slope, Slope width, Median stone size, Thickness × stone size, Price per ton |
| Main output | Rip rap needed |
| Formula | tons = area × depth/12 ÷ 27 × 1.4 |
| Cost | Free — no sign-up, no download |
How to use the Rip Rap Calculator
- 1Measure the length and the width of the slope face.
- 2Enter the median stone size class you are buying.
- 3Keep the thickness multiplier at 1.5–2 for most erosion work.
Inputs explained
- Length along slope(ft)
- Enter the length along slope you are working with.
- Slope width(ft)
- Enter the slope width you are working with.
- Median stone size(in)
- Enter the median stone size you are working with.
- Thickness × stone size(×)
- Enter the thickness × stone size you are working with.
- Price per ton($)
- Enter the price per ton you are working with.
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.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.