How Much River Rock for a 20×3 Bed?
A 20 × 3 ft bed (60 ft²) at 3″ deep needs 0.8 tons of river rock — 0.56 yd³ net plus 5% waste. Order 1.00 t — sold by the ton bulk; decorative rock often comes in 1-ton super sacks.
20×3 at other depths
| Depth | Volume | Order (tons) | 50 lb bag (0.5 ft³) |
|---|---|---|---|
| 2″ | 0.37 yd³ | 0.5 tons | 21 |
| 3″ (this page) | 0.56 yd³ | 0.8 tons | 32 |
| 4″ | 0.74 yd³ | 1.1 tons | 42 |
Other bed sizes
Order 1.00 t — sold by the ton bulk; decorative rock often comes in 1-ton super sacks.
- Area
- 60 ft²
- Volume (15.0 ft³)
- 0.56 yd³
- Net weight @ 1.35 t/yd³
- 1,500 lb · 0.75 t
- Waste / settling 5%
- + 0.04 t
- Order quantity
- 0.79 tons
- Truckloads
- 1 × tri-axle dump (≈20 t)
- Metric
- 0.42 m³ · 0.71 tonnes
- 50 lb bag (0.5 ft³)
- 32 bags
- Materials + delivery$80–$200 / ton · Sep 2026
- $170 – $290
- Installed (with labor)typ. $259
- $194 – $353
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What will this river rock job cost?
See the installed price range for these quantities and get up to 3 quotes from local contractors. Free, no obligation.
Different size or depth?
Open the full river rock calculator to change every input, pick a material and see truckloads.
How to calculate river rock by hand
Tons = Length (ft) × Width (ft) × Depth (in) ÷ 12 ÷ 27 × 1.35 t/yd³
Worked example
- Area: 20 ft × 4 ft = 80 ft².
- Volume: 80 ft² × (3 in ÷ 12) = 20 ft³ = 0.74 yd³.
- Weight: 0.74 yd³ × 1.35 t/yd³ = 1.0 ton.
- Waste 5%: 1.0 × 1.05 = 1.05 tons → order 1.25 tons.
- Bagged: 21 ft³ ÷ 0.5 ft³ = 42 × 50 lb bags.
- 1 ton of 1–3″ rock at 3″
- ≈ 80 ft²
- 1 ton of ¾–1″ rock at 2″
- ≈ 115 ft²
- 1 yd³ river rock
- ≈ 2,700 lb · 1.35 t
- Depth rule
- 1.5 × largest stone
Questions crews ask
How much river rock do I need?
Square feet × depth in inches ÷ 324 gives cubic yards; × 1.35 gives tons. A 20 × 4 ft border at 3″ needs 0.74 yd³, about 1 ton, or 42 × 50 lb bags. Order 1.25 tons bulk.
How deep should river rock be?
About 1.5 times the largest stone so the fabric never shows: 2″ for ¾–1″ rock, 3″ for 1–3″, 4″ for 3–5″ cobbles. Deeper wastes money and makes beds hard to weed; shallower shows fabric within a season.
How much does a ton of river rock cover?
Roughly 80 ft² at 3″ deep, 115 ft² at 2″, and 60 ft² at 4″. Larger stone leaves more voids, so 3–5″ cobbles cover slightly more per ton than the calculator’s 1–3″ default.