Rip Rap Calculator
Tonnage of rip rap for slopes and shorelines.
Enter your values
Enter the length along slope in ft.
Enter the slope width in ft.
Enter the median stone size in in.
Enter the thickness × stone size in ×.
Enter the price per ton in $.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Rip rap needed
- 70 tons
- Layer thickness
- 13.5 in
- Cubic yards
- 50 yd³
- Estimated cost
- $4,200.00
- Filter fabric
- 1,320 sq ft
Quick answer
Rip rap tonnage = area × thickness in feet × 1.4 tons per cubic yard equivalent, with thickness usually 1.5 to 2 times the median stone size.
tons = area × depth/12 ÷ 27 × 1.4
At a glance
| What it does | Tonnage of rip rap for slopes and shorelines. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Length along slope, Slope width, Median stone size, Thickness × stone size, Price per ton |
| Main output | Rip rap needed |
| Formula | tons = area × depth/12 ÷ 27 × 1.4 |
| Cost | Free — no sign-up, no download |
How to use the Rip Rap Calculator
- 1Measure the length and the width of the slope face.
- 2Enter the median stone size class you are buying.
- 3Keep the thickness multiplier at 1.5–2 for most erosion work.
Inputs explained
- Length along slope(ft)
- Enter the length along slope in ft.
- Slope width(ft)
- Enter the slope width in ft.
- Median stone size(in)
- Enter the median stone size in in.
- Thickness × stone size(×)
- Enter the thickness × stone size in ×.
- Price per ton($)
- Enter the price per ton in $.
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.
What do I need to enter into the Rip Rap Calculator?
Just 5 values: length along slope, slope width, median stone size, thickness × stone size, price per ton. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Rip Rap Calculator work out the 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. It applies the formula tons = area × depth/12 ÷ 27 × 1.4 and shows the working so you can check each step by hand.
Is the Rip Rap Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.