How Much River Rock Do I Need? Coverage & Buying Guide
A 100 sq ft landscape bed at 3 inches deep needs about 0.93 cubic yards (~1.25 tons) of river rock. Small river rock (3/4 in) starts around $27/ton bulk; decorative varieties run $75–$175/ton. Always install landscape fabric underneath decorative applications. Use code MEADOWLARK for 5% off bulk orders.
River rock is one of the easier landscape materials to work with, but it is surprisingly easy to over- or under-order. Bags are expensive for any real-sized project, and bulk orders come in by the ton — so knowing the conversion before you call a supplier matters.
This guide covers the formula, how depth works by use case, which size to pick, and what to install underneath for each application.
River Rock Calculator
Enter your project area and depth for a quick estimate. Use the results to compare bulk delivery against bag pricing.
Enter your dimensions above to calculate river rock needed.
💡 1 cubic yard of river rock covers approximately 100 sq ft at 3 inches deep
The Formula
River rock is sold by the cubic yard (bulk) or by the ton. The base formula:
Length (ft) × Width (ft) × Depth (in) ÷ 324 = Cubic Yards
To convert cubic yards to tons, multiply by 1.35 — the approximate weight of river rock per cubic yard. This is the same density as pea gravel and most rounded decorative stone.
Quick Reference: 3-Inch Depth
| Area | Cubic Yards | Tons |
|---|---|---|
| 50 sq ft | 0.46 yd³ | ~0.63 tons |
| 100 sq ft | 0.93 yd³ | ~1.25 tons |
| 200 sq ft | 1.85 yd³ | ~2.5 tons |
| 400 sq ft | 3.7 yd³ | ~5 tons |
| 1,000 sq ft | 9.26 yd³ | ~12.5 tons |
Always add 10% to your calculated amount for edges, irregular corners, and any depth variation across the area.
How Deep Should River Rock Be?
Depth is the single biggest variable in your estimate. Use the wrong depth and you either end up with a thin, patchy look or an unnecessarily expensive order.
| Application | Recommended Depth | Notes |
|---|---|---|
| Landscape beds (decorative) | 2–3 inches | 3 in is the sweet spot for appearance and weed suppression |
| Garden paths & walkways | 2–3 inches | Use edging to contain it — rock shifts without a border |
| Dry creek beds | 4–6 inches | Deeper fill looks more natural and stays put in rain |
| Under downspouts | 4–6 inches | Use 1–3 in or 2–5 in rock; small rock washes away |
| Drainage swales | 6+ inches | No landscape fabric; you need water to flow through |
| Erosion control slopes | 6–8 inches | Use 2–5 in rock on steeper grades |
Choosing the Right Size
River rock sizing is measured by diameter. The size affects both coverage and function — smaller stone fills tighter and looks neater; larger stone handles drainage and erosion better.
Small River Rock (3/4 inch)
The most popular size for residential landscape beds. It fills cleanly around plants, rakes easily, and creates a uniform finish. Works well for narrow beds and paths. Tends to scatter if used without edging. Shop bulk small river rock (use code MEADOWLARK for 5% off).
Medium River Rock (1–1.5 inch)
Good all-purpose size for larger landscape beds and moderate drainage areas. Stays in place better than the 3/4 inch stone under foot traffic and rain. The 1.5 inch river rock is a practical middle ground if you want something more substantial than the 3/4 inch but still manageable to spread and rake.
Large River Rock (1–3 inch)
The standard choice for dry creek beds and drainage channels. Large enough to look natural in a creek bed feature, and the variety in piece sizes creates a realistic look when combined with a few accent boulders along the banks. This is the size that holds up best under actual water flow. Shop 1–3 inch river rock.
Extra Large River Rock (2–5 inch)
For high-flow drainage areas, under downspouts with heavy volume, and erosion control on slopes. The size makes it impractical for regular landscape beds but ideal where water moves fast or a bold visual statement is the goal. Shop 2–5 inch river rock.
Landscape Fabric: Use It or Skip It
Whether to install landscape fabric under river rock depends entirely on the application.
Install landscape fabric:
- ✅ Decorative landscape beds and borders
- ✅ Garden paths and walkways
- ✅ Dry creek beds (decorative sections)
Skip landscape fabric:
- ❌ Drainage swales and erosion control
- ❌ Sections of dry creek beds that carry actual water
- ❌ Under downspout splash pads
Use woven landscape fabric, not the thin plastic film sold in some kits. Plastic blocks water from reaching plant roots, tears easily at edges, and creates more maintenance problems than it solves. Woven fabric lets water through, breathes, and lasts years longer.
Bags vs. Bulk: When Each Makes Sense
River rock bags at home improvement stores are convenient, but expensive by the cubic yard. A 0.5 cubic foot bag sells for $5–$8, which works out to $270–$432 per cubic yard. Bulk delivery by the ton typically runs $27–$90 per ton — which is $20–$67 per cubic yard, depending on the rock type.
| Project Size | Bags (0.5 cu ft) | Approx. Bag Cost | Bulk Delivery |
|---|---|---|---|
| Under 25 sq ft | 5–8 bags | $30–$65 | Minimum order often 1 ton — bags win here |
| 50–100 sq ft | 20–40 bags | $120–$320 | Bulk starts to win; compare local minimums |
| 200+ sq ft | 80+ bags | $500+ | Bulk delivery is clearly cheaper — usually 40–60% less |
For most landscape beds over 50 square feet, call a local supplier or check bulk pricing online. The minimum delivery amount is usually 1 ton, which covers about 74 sq ft at 3 inches deep — often enough to justify the call.
Before You Order
- ☐Measure your total area and add 10% — edges and irregular shapes always add up
- ☐Confirm your depth: 2–3 in for beds, 4–6 in for creek beds and drainage
- ☐Choose your size before ordering — switching after delivery is painful
- ☐Order landscape fabric and ground staples in advance and install before the rock arrives
- ☐Confirm dump truck access if ordering bulk — river rock is always delivered by weight
- ☐Compare bags vs. bulk for your project size — bulk wins for anything over about 50 sq ft
Calculate Your Project
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