River Rock Calculator

1. Choose the project shape. Select rectangle for most landscape beds, borders, and walkways. Use circle for tree rings, fire pit surrounds, or round garden beds. Pick "Total area" if you already measured the square footage from an irregular layout.
2. Enter your dimensions. Measure length and width in feet. For depth, most river rock ground cover uses 2 to 3 inches. Walkways and drainage areas need 3 to 4 inches. Use 4 or more inches for driveways or areas with heavy foot traffic. The river rock calculator converts inches to feet automatically.
3. Select the rock size. Choose the size closest to what you're ordering. Smaller 3/4 inch rock is lighter per cubic yard (1.3 tons) because pieces nest tightly. Larger 3 to 5 inch rock is heavier (1.6 tons) because of denser stone mass. If your supplier quotes a specific density, use "Custom density" and enter their number.
4. Set the waste factor. 10% is a safe default. Curved beds, tree rings, and areas around plants and edging always use more rock than the math predicts. I spread 3 to 5 inch rock around a drainage swale last year and the edges ate nearly 15% more than expected. Drop to 5% only for flat rectangular beds with clean edges.
5. Choose a bag size (optional). Select 0.5 or 1 cu ft bags if buying bagged river rock from a home center. Skip this for bulk delivery orders where you need cubic yards or tons.
6. Enter a price per ton (optional). Leave at 0 to skip cost. River rock typically costs $40 to $80 per ton in most US markets (2026), depending on size and color. Delivery adds $50 to $150 per load.
7. Review your results. The river rock calculator shows cubic feet, cubic yards, tons, bag count, and cost. Use cubic yards or tons when calling a supplier for bulk delivery. For small DIY projects, the bag count tells you how many bags to pick up at the store.

Pro tip: Measure each bed separately and add the totals before ordering. I once estimated a front yard by treating all three beds as one rectangle and over-ordered by almost a full cubic yard. Separate measurements catch the gaps between beds that you don't need to cover.

This river rock calculator uses three steps: area, volume, and weight. Each step builds on the previous one so you can trace how your measurements become tons and bags.

Volume:

Cubic feet = Area (sq ft) × Depth (ft)

Cubic yards = Cubic feet / 27

Weight:

Tons = Cubic yards × Density (tons per cubic yard)

Pounds = Tons × 2,000

Bags:

Bag count = Total cubic feet / Bag size (cu ft), rounded up to the next whole bag

With waste:

Order quantity = Base result × (1 + Waste % / 100)

Variables:

• Area = project surface in square feet (length × width for rectangles, π × radius² for circles)
• Depth = river rock layer thickness in feet (divide inches by 12)
• Density = weight of one cubic yard of river rock in tons (varies by rock size and moisture)
• Waste factor = percentage added for curves, edging, low spots, and spreading loss
• Bag size = volume per bag in cubic feet (typically 0.5 cu ft for decorative rock)

Density by rock size:

Example:

A landscape bed measures 20 × 10 feet at 3 inches deep, using 1-3 inch river rock.

• Area = 20 × 10 = 200 sq ft
• Depth in feet = 3 / 12 = 0.25 ft
• Cubic feet = 200 × 0.25 = 50 ft³
• Cubic yards = 50 / 27 = 1.85 yd³
• Tons = 1.85 × 1.5 = 2.78 tons
• With 10% waste = 2.04 yd³ / 3.06 tons (order quantity)

Most suppliers deliver river rock in 10 to 25 ton loads. At 3.06 tons, this project is a small delivery. Call ahead to confirm minimum order quantities, because some yards require at least 2 to 5 tons per trip.

Circle example:

An 8 foot diameter tree ring at 2 inches of 3/4 inch river rock.

• Radius = 8 / 2 = 4 ft
• Area = π × 4² = 50.3 sq ft
• Depth in feet = 2 / 12 = 0.167 ft
• Cubic feet = 50.3 × 0.167 = 8.40 ft³
• Cubic yards = 8.40 / 27 = 0.31 yd³
• Tons (3/4 in) = 0.31 × 1.3 = 0.40 tons
• Bags (0.5 cu ft) = 8.40 / 0.5 = 17 bags

For a project this small, bagged river rock from a home center is usually cheaper than bulk delivery after you add the delivery fee.

Quick coverage reference: One cubic yard of river rock at 2 inches deep covers about 162 sq ft. At 3 inches deep, it covers about 108 sq ft. Use the river rock calculator above to run your own numbers with different depths and rock sizes.

Assumptions:

• The project area has uniform depth. For uneven ground, measure depth at several points and use the average
• Density values are dry-weight averages. Wet river rock weighs 5% to 15% more, but suppliers typically price by dry weight
• Larger rock sizes need a deeper layer for full ground coverage. Use at least 2× the rock diameter as minimum depth
• Compaction is minimal for decorative river rock. The waste factor covers edge loss, low spots, and spreading around plants and edging
• For L-shaped or irregular beds, split into rectangles, calculate each section, then add the results before ordering