YardHow to use the river rock calculator
Calculate river rock
One cubic yard of river rock weighs about 1.45 tons (2,900 lb). Lay river rock at least twice as deep as the stone size so no soil or fabric shows through. Estimates only - confirm quantities with your supplier.
- Choose the shape of your area: rectangle, circle or triangle.
- Enter the length and width (or diameter) in feet.
- Enter the depth in inches. As a rule, lay river rock at least twice as deep as the stone size, so 4 inches suits common 1 to 3 inch rock.
- Read off the cubic yards, weight in tons and number of bags, then adjust the extra allowance if the ground is uneven.
River rock sizes and how deep to lay them
| Size | Typical uses | Lay this deep |
|---|---|---|
| 3/4 to 1 1/2 in | Planting beds, edging, around pools | 2–3 in |
| 1 to 3 in | Dry creek beds, drainage, beds | 3–4 in |
| 3 to 6 in | Creek beds, erosion control, accents | 6–8 in |
| 6 in and up (cobbles/boulders) | Feature rocks, retaining edges | Placed individually |
River rock is naturally rounded and smoothed by water, so colours vary from load to load and even within a load. That variation is the charm of it, but buy the whole job from one batch if the area is on show.
Where river rock works best
Dry creek beds are the classic river rock job: the stones look right, channel rainwater and stop erosion on slopes. River rock also excels in drainage swales, around downspouts, in low-maintenance planting beds, around pool equipment and as a mulch alternative where bark washes away. It is not a walking surface: the smooth stones roll underfoot and are hard on bare feet, so keep it off paths and play areas, where pea gravel or crushed stone serve better.
Coverage per cubic yard
| Depth | Coverage per cubic yard |
|---|---|
| 2 in | 162 sq ft |
| 3 in | 108 sq ft |
| 4 in | 81 sq ft |
| 6 in | 54 sq ft |
Tips before you order
- Always lay landscape fabric under river rock in beds; without it the stones slowly sink into the soil and disappear.
- Wash bagged river rock before placing it around plants or a pool; it usually arrives coated in quarry dust.
- Depth is the common mistake: one thin layer of 1 to 3 inch rock shows fabric between the stones. Budget two stones deep.
- For a dry creek bed, dig the channel first, line it with fabric, then place the biggest rocks along the edges and fill the middle with smaller ones.