River Rock Bed Calculator
Foundation beds and borders: 3″ of 1–3″ river rock over landscape fabric is the standard. Measure the bed length along the house and its average width. Irregular beds: break them into rectangles and add the areas.
Order 1.75 t — sold by the ton bulk; decorative rock often comes in 1-ton super sacks.
- Area
- 120 ft²
- Volume (30.0 ft³)
- 1.11 yd³
- Net weight @ 1.35 t/yd³
- 3,000 lb · 1.50 t
- Waste / settling 10%
- + 0.15 t
- Order quantity
- 1.65 tons
- Truckloads
- 1 × tri-axle dump (≈20 t)
- Metric
- 0.85 m³ · 1.50 tonnes
- 50 lb bag (0.5 ft³)
- 66 bags
- Materials + delivery$80–$200 / ton · Sep 2026
- $230 – $440
- Installed (with labor)typ. $400
- $280 – $572
Quantities follow the ticket. Links may earn us a commission at no cost to you; they never change a number.
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.
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 for a 40 ft foundation bed?
A 40 × 3 ft bed at 3″ is 30 ft³ = 1.1 yd³ ≈ 1.5 tons; with 10% extra order 1.75 tons or about 66 × 50 lb bags. You will also need 120 ft² of landscape fabric.
Should I put rock against my foundation?
Yes, with the grade sloping away from the house at 1″ per foot and the rock kept below the siding line. Rock beds against a foundation shed water better than mulch and do not hold moisture against the wall.
How do I keep river rock out of the lawn?
Edge it — steel, aluminium, brick or a paver soldier course. Round stone migrates without a restraint; a 4″ edge buried 1″ below the rock surface is enough.