River Rock Calculator
Estimate tons of river rock needed for a decorative landscape bed at your depth, and the total cost at your price per ton.
How this calculator works
River rock is sold by the ton like other bulk stone, converting your bed’s area and depth into cubic yards and then into weight using river rock’s density (1.4 tons per cubic yard). Because it’s a decorative material rather than a structural base, most beds only need a thin 2-inch layer.
Formula: Cubic yards = (Length ft × Width ft × Depth ft) ÷ 27. Tons = Cubic yards × 1.4.
Worked example
A 20 ft × 10 ft landscape bed at the standard 2-inch decorative depth, $80/ton:
- Depth in feet: 2 ÷ 12 = 0.167 ft
- Cubic yards: (20 × 10 × 0.167) ÷ 27 ≈ 1.235 yd³
- Tons: 1.235 × 1.4 ≈ 1.73 tons
- At $80/ton, that’s $138.27 before waste.
Coverage reference
| Depth | Coverage per ton |
|---|---|
| 1 in | ~231 sq ft |
| 2 in | ~116 sq ft |
| 3 in | ~77 sq ft |
How to measure your area
Measure the length and width of the bed you’re covering, not including any border or edging material. For irregular beds, break the shape into rectangles, calculate each separately, and add the tons together — or run the calculator once per section using its own dimensions.
Frequently asked questions
Why is river rock more expensive than crushed gravel?
River rock is a decorative, rounded stone typically sold for landscape beds rather than structural base material, so it's priced closer to $80/ton versus $40-45/ton for construction gravel like crushed stone or crusher run.
How deep should a river rock layer be?
2 inches is the standard depth for a decorative landscape bed — enough to cover the ground and suppress weeds without wasting material. Drainage or erosion-control applications sometimes go deeper, up to 3-4 inches.
Do I need landscape fabric under river rock?
Yes, it's strongly recommended. Fabric keeps the rock from sinking into the soil over time and blocks weeds from growing up through the gaps between the rounded stones.
Is river rock's density different from other gravel?
River rock runs about 1.4 tons per cubic yard, similar to crushed stone but slightly less dense than crusher run, since the rounded stones don't interlock as tightly as angular, fines-packed material.
What size river rock should I use for a landscape bed?
1-2 inch river rock is the most common decorative size — large enough to stay put in wind and rain, small enough to look refined. Larger 3-5 inch rock is used more for accents or drainage swales than full bed coverage.
Estimates only. Verify quantities with your supplier before purchasing.