What is the density of river rock?

River rock (smooth, rounded natural stone) has a typical bulk density of around 1,682 kg/m³ (105 lb/ft³). Exact density varies slightly with rock size and how tightly the stones pack together; this calculator uses 1,682 kg/m³ as the standard value, with adjusted densities for smaller and larger size variants.

How is volume calculated?

For rectangular areas: Volume = Length × Width × Depth. For circular areas: Volume = π × (Diameter / 2)² × Depth. All dimensions are converted to the same unit before multiplying.

How do I convert cubic yards to tons?

Multiply the volume in cubic yards by the density in tons per cubic yard. For river rock at 1,682 kg/m³, one cubic yard weighs approximately 1.41 short tons. This calculator handles the conversion automatically.

How deep should I lay river rock?

For decorative ground cover and garden beds, 2–3 inches (5–8 cm) is standard. For pathways where foot traffic is expected, use 3–4 inches (8–10 cm). For erosion control and drainage applications, 4–6 inches (10–15 cm) or more may be required.

Why should I add a waste factor?

Some rock is inevitably lost during delivery, spreading, and settling. A 5–10% waste factor ensures you order enough material to complete the project without a costly second delivery.

How many bags of river rock do I need?

Divide the total weight in pounds by the bag weight shown on the product. Common bag sizes are 0.5 cu ft (about 50 lb) and 0.4 cu ft. Alternatively, divide your cubic feet result by the coverage per bag listed on the packaging.

How much area does a 50 lb bag of river rock cover?

A 50 lb bag of river rock holds about 0.5 cubic feet. At a 2-inch depth, that covers roughly 3 square feet; at a 3-inch depth, about 2 square feet. Coverage drops with deeper layers because the same volume spreads thinner over a smaller footprint.

How much is 3 yards of river rock?

3 cubic yards equals 81 cubic feet, weighs about 4.2 short tons (8,400 lb), and covers roughly 485 sq ft at a 2-inch depth or 325 sq ft at a 3-inch depth. Delivered bulk pricing varies by region but typically runs $50–$150 per cubic yard plus delivery.

River Rock Calculator

Calculate the volume and weight of river rock needed to cover any rectangular or circular area at a given depth.

Area & Depth

Length (ft)

Width (ft)

Depth (in)

Waste Factor (%)

River Rock Size

Summary

A free online river rock calculator that estimates the volume (cubic yards, cubic feet, cubic meters) and weight (tons, pounds, kilograms) of decorative river rock required for your landscaping or construction project. Enter your area dimensions and desired depth, choose a rock size variant to apply the correct bulk density, and optionally add a waste factor for precise ordering. Supports both Imperial and Metric units.

How it works

Select your area shape: rectangular or circular.
Choose Imperial (feet/inches) or Metric (meters/centimeters) units.
Enter the length and width (or diameter for circular), then the desired rock depth.
Select a river rock size to apply the appropriate bulk density for weight estimates.
Add a waste factor (5–10% recommended) to account for spillage and settling.
Click Calculate to see volume in cubic yards, cubic feet, and cubic meters, plus total weight.

Use cases

Estimating river rock for a garden bed or landscape border.
Calculating decorative stone for a dry creek bed or water feature.
Planning river rock coverage for a pathway or patio surround.
Ordering the correct tonnage of river rock for erosion control.
Budgeting decorative stone quantities for a backyard project.
Computing rock fill for drainage swales and French drains.
Calculating how many bags of river rock to purchase at a home center.
Planning stone mulch as a low-maintenance lawn alternative.

Frequently Asked Questions

Last updated: 2026-05-25 · Reviewed by Nham Vu