River Rock Calculator
A 100 square foot bed at 2 inches deep needs about 0.68 cubic yards of river rock with 10% extra, which is roughly 0.92 tons or 37 half-cubic-foot bags. Enter your area, depth, and density to estimate how much river rock to order for borders, planting beds, dry creek beds, or drainage strips.
Quick answer
River rock volume comes from area times depth.
What this tells you
- •River rock volume comes from area times depth.
- •Cubic yards help with bulk delivery quotes, while tons help when suppliers sell by weight.
- •The default density is 100 lb/ft3, which is a practical loose-fill estimate for many decorative river rock blends.
- •Bag count uses the bag size you enter and rounds up so you do not run short.
How to Use
- 1Enter the area you want to cover in square feet.
- 2Enter the finished river rock depth in inches.
- 3Adjust the density if your supplier lists a different lb/ft3 value.
- 4Set bag size and waste allowance if you are pricing bagged stone or want extra for touch-ups.
- 5Click Calculate to compare cubic yards, tons, pounds, and bags.
How It Works
Formula
Volume (cu ft) = Area x Depth(ft)
Cubic Yards = Volume / 27
Weight (lb) = Volume with Waste x Density
Tons = Weight / 2,000
Bags = ceil(Volume with Waste / Bag Size)The calculator converts depth from inches to feet, multiplies by area for volume, adds the waste allowance, then converts the final loose-fill volume to pounds, tons, and bag count.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Planting bed with bagged river rock
This is a typical shallow decorative bed where bag count matters as much as bulk volume.
Dry creek bed with a heavier stone
A deeper creek-bed style install needs more tonnage, so the supplier density makes a visible difference.
Approximate River Rock Coverage by Weight
Coverage below assumes loose river rock at 100 lb/ft3 and no waste allowance.
| River Rock | Cubic Yards | At 2 in Depth | At 3 in Depth |
|---|---|---|---|
| 0.5 ton | 0.37 yd3 | 60 sq ft | 40 sq ft |
| 1 ton | 0.74 yd3 | 120 sq ft | 80 sq ft |
| 2 tons | 1.48 yd3 | 240 sq ft | 160 sq ft |
| 3 tons | 2.22 yd3 | 360 sq ft | 240 sq ft |
If your supplier gives a different bulk density, adjust the ton coverage up or down to match that material.
Bulk River Rock vs Bags
Bags are easy for a narrow border, a mailbox ring, or a small repair where you only need a few cubic feet. They are also simpler when access is tight and you do not want a bulk pile dropped on the driveway.
Bulk delivery starts to make more sense once you are around 1 cubic yard or more. That is 27 cubic feet of stone, which equals 54 half-cubic-foot bags before waste, so the handling effort climbs fast.
Suppliers may quote decorative stone by the cubic yard, by the ton, or both. The safest approach is to carry both numbers into the quote request and compare them against the density that yard uses for that exact river rock size.
Common mistakes
- Entering the footprint of a curved bed without accounting for the actual square footage
- Using a compacted or wet weight number when the yard is quoting loose decorative rock
- Comparing bag count to bulk yardage without checking the bag size on the label
- Skipping extra material for settling, grade changes, edging, and touch-up work around plants