Side by side
| River Rock | Mulch | |
|---|---|---|
| Weight per cubic yard | 2,800 lb (1.40 t) | 506 lb (0.25 t) |
| Cubic yards per ton | 0.71 | 3.95 |
| Sq ft per ton at 3 in | 77 | 427 |
| Average price | $45–$130/ton, $50–$160/yd³ | $50–$150/yd³ |
Weights and prices from the sources listed below.
Mississippi State Extension lists gravel, pebbles and stones as inorganic mulch that is inexpensive and permanent; organic mulch breaks down and adds organic matter. Kentucky Extension caps organic mulch at 3 inches; Earthstone lists 2 to 4 inches for river rock beds.
Working it out
Cubic yards = area × depth ÷ 324 (sq ft and inches). Tons = cubic yards × weight per cubic yard.
For 200 sq ft at 3 inches, both need 1.85 cubic yards: 2.59 tons of river rock or 0.47 tons of mulch.
Common questions
Which is heavier, river rock or mulch?
River Rock at about 1.40 tons per cubic yard, against 0.25.
Sources
- https://extension.msstate.edu/publications/mulches-for-the-landscape
- https://publications.ca.uky.edu/sites/publications.ca.uky.edu/files/ho106.pdf
- https://www.earthstonerock.com/pages/frequently-asked-questions
- https://hellogravel.com/guides/2025-gravel-prices-per-ton-delivered-cost-calculator-and-regional-rates/
- https://www.thecalculatorsite.com/articles/units/how-much-cubic-yard-weigh.php
- https://homeguide.com/costs/gravel-prices
- https://www.homeadvisor.com/cost/landscape/deliver-soil-mulch-or-rocks