River Rock Calculator
Calculate how much river rock or decorative stone you need in cubic yards, tons, and bags for landscaping projects. See also our Crushed Stone Calculator, Gravel Calculator, and Mulch Calculator.
Area Input
How to Use the River Rock Calculator
Enter your project area as length × width or total square footage, specify the desired depth in inches, and select the rock size. Larger rocks require greater depth for full coverage and have lower coverage rates per ton due to air gaps between stones. The calculator provides results in cubic yards (for bulk ordering), tons (for weight-based pricing), and number of 50-lb bags (for retail purchases at home improvement stores).
Formula
Volume (cu ft) = Area (sq ft) × Depth (in) / 12
Cubic Yards = Volume / 27
Tons = Cubic Yards × Density
Bags (50 lb) = (Tons × 2000) / 50
River Rock Density: 1.2 - 1.3 tons/cu yd
Example Calculation
Garden bed: 15 ft × 10 ft, 3" deep, 2-4" river rock
Area = 150 sq ft
Volume = 150 × (3/12) = 37.5 cu ft
Cubic Yards = 37.5 / 27 = 1.39 yd³
Tons = 1.39 × 1.25 = 1.74 tons
Bags = (1.74 × 2000) / 50 = 70 bags
Coverage per ton at 3" depth = 60 sq ft
Reference Table — Rock Sizes and Coverage Rates
| Rock Size | Coverage/Ton @ 2" | Coverage/Ton @ 3" | Min Depth | Best Use |
|---|---|---|---|---|
| 1-2 inch | 120 sq ft | 80 sq ft | 2" | Ground cover, borders |
| 2-4 inch | 90 sq ft | 60 sq ft | 3" | Landscaping, dry creek beds |
| 4-8 inch | 65 sq ft | 45 sq ft | 4" | Accent areas, water features |
| 8-12 inch | 50 sq ft | 35 sq ft | 8" | Focal points, erosion control |
| Polished (1-2") | 110 sq ft | 75 sq ft | 2" | Decorative, zen gardens |
| Mexican Beach | 100 sq ft | 70 sq ft | 2" | Premium landscaping |
Frequently Asked Questions
How deep should river rock be for landscaping?
For 1-2 inch river rock, use 2-3 inches of depth. For 2-4 inch rock, use 3-4 inches. For larger 4-8 inch rock, use at least 4-6 inches. The general rule is the depth should be at least 2× the rock diameter to prevent soil from showing through and to create a natural appearance.
How much does river rock cost?
River rock costs $40-$75 per ton for bulk delivery or $4-$8 per 50-lb bag at retail stores. Polished or specialty colors cost $75-$150 per ton. Mexican beach pebbles are premium at $100-$200 per ton. Buying in bulk (by the ton) is significantly cheaper than bags for projects over 100 sq ft.
Should I use landscape fabric under river rock?
Yes, always install commercial-grade woven landscape fabric under river rock. This prevents weeds, stops rocks from sinking into soil, and makes future removal easier. Use fabric with at least 3 oz/sq yd weight. Pin it every 12 inches and overlap seams by 6 inches.
What size river rock is best for a dry creek bed?
For a natural-looking dry creek bed, use a mix of 2-4 inch and 4-8 inch river rock. Place larger stones along the edges and at curves, with smaller stones filling the center channel. Add a few 8-12 inch accent boulders at key points for a realistic appearance.
How many bags of river rock do I need?
A 50-lb bag of river rock covers approximately 2-4 sq ft at 2 inches deep, depending on rock size. For a 100 sq ft area at 3 inches deep, you'll need approximately 50-70 bags. For projects larger than 200 sq ft, bulk delivery by the ton is more economical.
Does river rock attract bugs or snakes?
River rock is less likely to attract insects than organic mulch since it doesn't decompose or retain moisture. However, the gaps between larger rocks can provide shelter for small creatures. To minimize this, use landscape fabric underneath, maintain a clean border, and avoid placing rock directly against your home's foundation.