Aggregates calculator
River Rock Calculator
Calculate river rock volume, tons to order, and material plus delivery cost from the layer dimensions.
Planning estimate, not a contractor quote. Review the assumptions and replace presets with local prices when available.
Method
How this calculator works
Use this tool for decorative stone around beds and drainage features. Larger stones can leave more void space and create a less even layer. Obtain a coverage or bulk-density figure for the actual size, rather than treating all river rock as one product. Keep the finished layer, loose delivery volume, and rounded weight distinct so you can compare the estimate with the supplier’s quote.
Finished ft³ = length × width × depth in inches ÷ 12. Loose ft³ = finished ft³ × (1 + allowance ÷ 100). US tons = loose ft³ × loose density ÷ 2,000. Round up to the supplier’s weight increment.
Worked example
A realistic starting point
A 20 × 10 ft layer at 3 inches is 50 ft³. With zero loose-volume allowance and an illustrative density of 100 lb/ft³, it weighs 2.5 US tons. A 0.5-ton ordering increment leaves the order at 2.5 tons. Enter the actual product density and quoted price.
What changes the answer
Factors worth checking
Measure the filled layer
Use the intended material depth rather than excavation depth. For an irregular shape, split it into measured rectangles and reconcile the total with your plan before ordering.
Stone size and coverage
A nominal two-inch depth does not automatically describe a uniform bed of large stones. Confirm the intended bed thickness before treating volume as an order.
Round the purchase, then price it
The material subtotal uses the rounded supplier order. Delivery is added once. If the supplier sells in a different increment or includes delivery in the unit price, update those inputs to avoid double counting.
Common questions
River Rock FAQ
Does the calculator design a drainage trench?
No. It estimates a filled layer. Trench geometry, drainage capacity, filters, pipe, and outlet design must be established separately.
Why can a supplier quote more than the calculated exact weight?
Minimum loads and order increments can increase the purchased amount. The calculator exposes its increment; confirm any separate supplier minimum.
Can I compare two products?
Use the comparison controls with the density, allowance, and price for each product. Similar weights do not mean the products are suitable for the same application.
Evidence
Sources & review
- Mulzer Crushed Stone — aggregate calculatorSupplier context for material-dependent bulk density and estimating limits.
- NIST — SI units: volumeUnit relationships; supplier product coverage and prices remain separate inputs.
Published by Calcstead. Report a correction.
Method and source links reviewed September 6, 2026. Price presets are editable planning inputs and should be replaced with current local information.