Calculate riprap stone tonnage for slopes, channels, and shorelines. Enter area and thickness for accurate stone weight estimates.
Riprap is large angular stone used to armor slopes, channels, shorelines, and structures against erosion from water flow. It's a permanent erosion control solution that outperforms blankets and vegetation in high-energy environments where water velocity or wave action would wash away lighter materials.
This calculator estimates the riprap tonnage needed based on the area to be protected and the stone layer thickness. Standard riprap classifications range from Class I (6-inch stone) to Class VI (36-inch stone), with layer thickness typically 1.5 to 2 times the median stone diameter.
Whether you're protecting a culvert outlet, lining a drainage channel, or stabilizing a pond bank, this tool converts your area and thickness into the cubic yards and tons of riprap to order.
This data-driven approach helps contractors minimize rework, avoid delays caused by material shortages, and deliver projects on time and within the agreed budget. By quantifying this parameter precisely, construction teams can optimize material orders, reduce on-site waste, and ensure structural requirements are met safely and efficiently.
Riprap is sold by the ton, and the tonnage depends on area, thickness, and stone density. This calculator bridges those variables so you can get an accurate quote from your stone supplier. Data-driven calculations reduce financial risk by ensuring that material orders, labor estimates, and project budgets reflect actual requirements rather than rough approximations.
Volume (ft³) = Area (ft²) × Thickness (ft) Volume (yd³) = Volume (ft³) ÷ 27 Weight (tons) = Volume (yd³) × Density (tons/yd³)
Result: 44.4 yd³ / 66.7 tons
800 sq ft at 18 inches (1.5 ft) thick = 1,200 ft³ = 44.4 yd³. At 1.5 tons per yd³, that's 66.7 tons. Order ~73 tons (+10%) for irregular placement.
Riprap is classified by median stone diameter (D50): Class I (6 in), Class II (9 in), Class III (12 in), Class IV (18 in), Class V (24 in), Class VI (36 in). Each class has a grading range with minimum and maximum sizes for proper interlocking.
Common riprap applications: culvert outlets and inlets, channel linings, bridge abutments, shoreline protection, dam spillways, slope stabilization, and stormwater outfall protection. Each has specific sizing and thickness requirements.
Beneath riprap, install either a non-woven geotextile fabric or a graded stone filter layer. Geotextile is standard for most applications. For high-velocity flows, a granular filter layer is preferred because fabric can tear if stones shift.
When riprap is placed on slopes, remember to calculate the actual slope area (not the plan-view area). Slope area = plan area ÷ cos(slope angle). For a 2:1 slope, the surface area is about 12% more than the plan-view area.
Riprap size depends on water velocity. Low flows (under 5 fps): 6‒12 inch stone. Moderate flows (5‒10 fps): 12‒18 inch. High flows (10‒15 fps): 18‒24 inch. Very high flows or wave action may need 24‒36 inch stone.
The layer thickness should be at least 1.5 times the maximum stone diameter, with a minimum of 12 inches. For example, if using 12-inch stone, the layer should be at least 18 inches thick.
Riprap costs $25–$75 per ton depending on stone size and location. Delivery adds $5–15 per ton. Class I (small) is cheapest; Class V–VI (large) is most expensive. Placement labor adds $30–60 per ton.
Yes, almost always. A non-woven geotextile filter fabric prevents soil from migrating up through the stone voids, which would undermine the riprap layer. This is a standard engineering requirement.
Placed riprap (including voids) weighs 1.3–1.6 tons per cubic yard, depending on stone type and void ratio. Granite is heavier (~1.5 tons/yd³). Limestone is slightly lighter (~1.4 tons/yd³). Use your supplier's density.
Yes, riprap creates attractive, low-maintenance landscape features. Use it around ponds, along drainage swales, in dry creek beds, and as decorative borders. Smaller classes (6‒12 inch) work best for residential landscaping.