Understanding Rock Coverage
Landscaping rock is typically sold by weight (tons) or volume (cubic yards). This calculator first determines the total volume of your area in cubic feet based on its length, width, and desired depth.
It then converts this volume into cubic yards (1 cubic yard = 27 cubic feet) and tons. The weight can vary slightly based on the type and size of the rock, but a standard estimate is that 1 cubic yard of river rock weighs about 1.2 to 1.4 tons. Our calculator uses an average of 1.3 tons for its estimate.
Recommended Depth by Rock Size
| Rock Size | Recommended Depth | Notes |
|---|---|---|
| 3/8" to 1/2" (Pea Gravel) | 2 inches | Good for walkways and patios. A 2-inch depth ensures full coverage. |
| 1" to 2" | 3 inches | Most common size for general ground cover and garden beds. |
| 2" to 4" | 4-5 inches | Creates a more substantial, textured look. Best for preventing weed growth. |
How to Use the Calculator
- Measure the length and width of the area you want to cover with rock.
- Decide on the depth of the rock layer. See the table above for recommendations based on rock size.
- Enter the price per ton from your local landscape supplier.
- Click "Calculate Rock Needed" to get a full estimate of volume, weight, and cost.
Frequently Asked Questions
What if my area is circular?
For a circular area, measure the radius (distance from the center to the edge). Calculate the area using the formula: Area = π × radius². For example, if your circle has a 10-foot radius, the area is 3.14159 * (10*10) = 314.16 sq. ft. You can then find a rectangle with a similar area (e.g., 31.4 ft long by 10 ft wide) to use in the calculator.
How many bags of rock do I need?
A standard bag of decorative rock is typically 0.5 cubic feet. The calculator provides the total cubic feet needed ("Volume (Cubic Feet)"). Simply divide that number by 0.5 to determine the number of bags you would need to buy.