Rip Rap Calculator
Use this rip rap calculator to estimate the stone volume, weight, and tonnage needed for slope protection, erosion control, and drainage armor. It is helpful when you need a quick bank-protection takeoff before ordering stone.
Result
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What This Rip Rap Calculator Helps You Do
Use this rip rap calculator to estimate the stone volume, weight, and tonnage needed for slope protection, erosion control, and drainage armor. It is helpful when you need a quick bank-protection takeoff before ordering stone.
How to Calculate Rip Rap Calculator
- Measure the rip rap inputs - Enter the dimensions, spacing, density, or thickness values that define the rip rap volume, weight, and tonnage.
- Check the units - Keep every input in the same unit system so the output stays consistent and easy to compare.
- Choose the solve mode - Select the output you want, such as length, weight, volume, posts, or cost.
- Read the output - Use the main result and the extra detail rows to verify the estimate before you order materials or build.
Rip Rap Calculator Formula
| Symbol | Definition | Unit |
|---|---|---|
| L | Slope length | ft |
| H | Slope height | ft |
| T | Stone thickness | ft |
| ρ | Stone density | lb/ft3 |
| w | Waste multiplier | x |
Worked Examples
- length: 20
- height: 8
- thickness: 1
- density: 105
- wasteMultiplier: 1.1
Result: Rip rap tonnage = 9.24 tons
A riverbank slope is easiest to compare when the stone tonnage is known. The estimate is 9.24 tons.
- length: 15
- height: 6
- thickness: 0.75
- density: 100
- wasteMultiplier: 1.08
Result: Rip rap volume = 72.90 ft3
Volume is the first step before ordering stone by weight. The estimate is 72.90 ft3.
- length: 30
- height: 5
- thickness: 1.2
- density: 110
- wasteMultiplier: 1.12
Result: Rip rap weight = 22176.00 lb
A roadside ditch can absorb a lot of stone, so weight matters early. The estimate is 22176.00 lb.
- length: 24
- height: 10
- thickness: 1.1
- density: 108
- wasteMultiplier: 1.15
Result: Rip rap tonnage = 16.39 tons
Embankments are best compared in tons because delivery is often weight-based. The estimate is 16.39 tons.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| < 10 tons | Small protection zone | Often a localized erosion-control job. |
| 10–50 tons | Typical slope armor | Common for drainage swales and smaller banks. |
| > 50 tons | Large bank protection | Review haulage, access, and placement method. |
Frequently Asked Questions
Sources
Last reviewed: March 2026