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Rip Rap Calculator

Construction

Calculate how many tons and cubic yards of rip rap you need for erosion control. Enter area dimensions and depth to get an accurate stone quantity estimate.

1500
1500
348
1.21.8

Rip Rap Needed (tons)

16.67
Volume (cubic yards)
11.11

This calculator computes your Rip Rap Needed (tons), Volume (cubic yards) from the values you enter.

Inputs
LengthWidthDepthDensity
Outputs
Rip Rap Needed (tons)Volume (cubic yards)

What is a Rip Rap?

A Rip Rap Calculator estimates the tonnage and volume of large erosion-control stone needed to cover a bank, slope, or shoreline to a specified depth. Rip rap is coarse, angular rock — usually 6 to 24 inches across — placed along stream banks, pond edges, culvert outlets, and steep slopes to prevent soil from washing away under moving water.

Because rip rap is sold and priced by the ton, and delivery costs scale with quantity, getting the estimate right before ordering matters for both budget and project timing. This calculator converts your area's length, width, and depth into cubic yards, then applies a density figure specific to your stone type to produce a tonnage figure you can hand directly to a quarry or landscape supplier. For decorative rather than structural stone needs, see the River Rock Calculator instead.

How to use this Rip Rap calculator

  1. Enter the Length of the area to be covered, in feet.
  2. Enter the Width of the area, in feet.
  3. Enter the Depth of the rip rap layer, in inches — 12 in is a common default for moderate erosion control.
  4. Adjust the Density slider to match your supplier's tons-per-cubic-yard figure for the specific stone type, typically 1.2-1.8.
  5. Read the Rip Rap Needed (tons) result to place your order, and check Volume (cubic yards) to compare against cubic-yard pricing.

Formula & Methodology

The calculation converts area and depth into cubic yards, then applies stone density:

Cubic feet = Length x Width x (Depth ÷ 12)

Cubic yards = Cubic feet ÷ 27

Tons needed = Cubic yards x Density (tons/yd³)

Worked example: A 30 ft by 10 ft stream bank section with a 12 in rip rap depth and a density of 1.5 tons/yd³:
- Cubic feet = 30 x 10 x (12 ÷ 12) = 300 ft³
- Cubic yards = 300 ÷ 27 = 11.11 yd³
- Tons needed = 11.11 x 1.5 = 16.67 tons

At a typical delivered price of $50/ton, this project would cost roughly $833 in stone alone, before filter fabric or placement labor.

Frequently Asked Questions

The amount depends on the area you're covering and the depth of the stone layer — a typical 30 ft by 10 ft bank with a 12 in depth needs roughly 16-17 tons. Enter your exact length, width, and depth into the Rip Rap Calculator to get a precise tonnage for your project.
First find the volume in cubic feet by multiplying length x width x depth (with depth converted from inches to feet). Divide by 27 to get cubic yards, then multiply by the stone's density in tons per cubic yard to get the total tons needed.
Rip rap consists of large, angular stones — typically 6 in to 24 in across — used specifically for erosion control on slopes, stream banks, and shorelines. Gravel refers to much smaller aggregate used for driveways, drainage, and base layers; use the [Gravel Calculator](/gravel-calculator/) for those projects instead.
Most erosion control applications call for a rip rap layer 1.5 to 2 times the diameter of the largest stone, commonly 12-18 in deep. Steeper slopes or higher water flow velocities generally require a thicker layer for adequate protection.
Rip rap typically weighs 1.4 to 1.6 tons per cubic yard depending on the stone type, with granite and limestone at the denser end. If your supplier provides a specific density figure, use that value in the Density input for the most accurate result.
Yes, measure the length along the bank and the width as the horizontal distance the rip rap needs to cover up the slope. For sloped applications, measure along the surface of the slope rather than a flat horizontal distance to avoid underestimating material.
Rip rap in the US typically costs $35-$100 per ton delivered, depending on stone size, region, and delivery distance from the quarry. Larger stone classes used for heavy erosion control cost more than smaller decorative-grade rip rap.
Yes, geotextile filter fabric is standard practice under rip rap to prevent the underlying soil from washing out through the gaps between stones. Factor this into your project budget alongside the stone tonnage from this calculator.
Most quarries and suppliers sell and price rip rap by the ton, though some also quote cubic yard pricing for bulk orders. This calculator gives you both figures so you can compare quotes either way.
Rip rap is large, angular, functional stone sized for erosion control and structural stability. [River rock](/river-rock-calculator/) is smaller, rounded, and used mainly for decorative landscaping, drainage swales, and ground cover rather than heavy-duty bank protection.
Stone size depends on the water flow velocity or slope steepness at your site — steeper slopes and faster water need larger, heavier stone to resist being washed away. A civil engineer or erosion control specialist can recommend the right stone class (often labeled Class I through Class V) for your specific site conditions.
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