Gravel Calc ProRiver Rock Calculator
Set the bed shape, size and depth. The tool shows river stone in tons, cubic yards and bags.
Bags, weight, waste and cost
Use the weight your supplier gives for the exact stone. The material list sets a starting value.
You need
0 cubic yards
0 sq ft at 0 in deep
- Tons
- 0
- Cubic feet
- 0
- Bags
- 0
- Pounds
- 0
- Cubic meters
- 0
- Metric tonnes
- 0
- Cost
- 0
- 1 ton covers
- 0
By the Gravel Calc Pro team · Weights from producer data sheets · Math covered by unit tests · Last updated October 22, 2026 · How we calculate
How do I calculate river rock?
Find the area in square feet. Multiply it by the depth in inches and divide by 324 to get cubic yards. Multiply by 1.35 for tons. A 4 by 20 foot border at 3 inches deep is 0.74 cubic yards. That is about 1 ton, or 40 bags of 0.5 cubic feet.
tons = cubic yards × 1.35
bags = area × depth ÷ 12 ÷ bag size
Beds around trees are often rings. Use Circle for the outer ring, then subtract the area of the trunk circle. A round bed 8 feet across is 50.3 square feet. A 1 foot trunk takes away 0.8 square feet.
Weight of river pebbles
This kind of round stone weighs about 1.35 tons per cubic yard, or 100 pounds per cubic foot, based on bagged river pebbles. That is a bit less than crushed stone, since round stones leave more open space between them than angular pieces that pack tight.
The Vigoro River Pebble bag lists 0.5 cubic feet and 50 pounds. It also says one bag covers 2 square feet at 3 inches deep. That matches the math: 0.5 cubic feet spread 0.25 feet thick covers 2 square feet. QUIKRETE River Pebbles also come in 0.5 cubic foot bags.
River rock coverage chart
| Depth | 1 cubic yard covers | 1 ton at 1.35 t/yd³ covers |
|---|---|---|
| 2 in | 162 sq ft | 120 sq ft |
| 3 in | 108 sq ft | 80 sq ft |
| 4 in | 81 sq ft | 60 sq ft |
| 6 in | 54 sq ft | 40 sq ft |
| 8 in | 41 sq ft | 30 sq ft |
The UC Master Gardener rule of thumb is that a ton of gravel covers 80 to 120 square feet at 2 inches. Round pebbles at 1.35 tons per yard land at the top of that range.
Stone size and depth
Size changes the depth you need. A layer should cover the soil with no gaps. Small stones do that in a thin layer. Big stones need a thicker one.
| Rock size | Common use | Start at |
|---|---|---|
| Under 1 in (pebbles) | Paths, pots, small beds | 2 in |
| 1 to 2 in | Flower beds, borders | 3 in |
| 2 to 3 in | Downspouts, slopes | 4 in |
| 3 to 6 in cobbles | Dry creek beds | 6 in or more |
These are starting points. Lay out one bag in a test patch and see if the soil shows through.
Building a dry creek bed
- Dig a shallow channel that follows the path water already takes.
- Line it with fabric, then place large cobbles along the edges.
- Fill the center with smaller river stone. Work out each size as its own area.
Other rock options
Need something to walk on? Round stone shifts, so a crushed stone path is firmer. For small, smooth stone in a patio, see the pea gravel calculator. For lava rock, marble chips and other mixes, try the landscape rock calculator.
Common questions
How many bags of river rock do I need?
Divide the cubic feet by the bag size. A 0.5 cubic foot bag of Vigoro River Pebble covers 2 square feet at 3 inches deep. So a 4 by 10 foot bed, which is 40 square feet, needs 20 bags at 3 inches.
How much area does one ton cover?
At 1.35 tons per cubic yard, one ton covers about 80 square feet at 3 inches, 60 square feet at 4 inches and 40 square feet at 6 inches. Larger rock needs a deeper layer, so it covers less per ton.
What does a cubic yard of river stone weigh?
Based on a 50 pound, 0.5 cubic foot bag of river pebbles, a cubic yard weighs about 2,700 pounds, or 1.35 tons. Bulk rock from a quarry can be a bit lighter or heavier, so check the supplier number.
How deep should the stone layer be?
The layer should be deep enough that no soil shows. Small pebbles can do that at 2 to 3 inches. Bigger stones need a deeper layer. This tool starts 2 to 3 inch rock at 4 inches and dry creek cobbles at 6 inches. Test one bag in a small patch first.
Should I lay landscape fabric under the stones?
It helps keep the stone clean and stops it from sinking into mud. Weeds can still sprout from seeds that land on top. The UC Master Gardener article on gravel says to use the heaviest fabric you can get if you choose to use it.