How Much River Rock for an 18 Foot Circle?
Round areas such as fire pit patios, tree rings and seating circles use less stone than a square of the same width. An 18-foot circle is about 254.5 square feet; at 3 inches that is 3.2 tons of river rock.
Volume and tonnage calculator →The math
- Area: 254.5 sq ft.
- Depth in feet: 3 ÷ 12 = 0.250 ft.
- Cubic yards: 254.5 × 0.250 ÷ 27 = 2.36 yd³.
- Tons: × about 1.35 tons per yard = 3.2 tons.
The gravel calculator does this for any size.
Related: How Much Gravel for an 18 Foot Circle?
River rock needed by depth
| Depth | Cubic yards | Tons of river rock | Tons +10% |
|---|---|---|---|
| 2 in | 1.57 | 2.1 | 2.3 |
| 3 in | 2.36 | 3.2 | 3.5 |
| 4 in | 3.14 | 4.2 | 4.7 |
| 6 in | 4.71 | 6.4 | 7.0 |
Using a circle of stone
A round gravel area is easy to lay out with a stake and string at the center. Set flexible edging along the line and lay fabric inside before the stone goes in. For a fire pit area, keep combustibles well away and check local burn rules.
Related: How Much Crushed Stone for an 18 Foot Circle?
Ordering and delivery
Most quarries and landscape yards deliver by the ton; ask whether there is a minimum and a delivery fee, and where the driver can dump without damaging your lawn. River rock is smooth and decorative; larger sizes cover less area per ton at the same depth. Round up by about 10 percent for compaction and uneven ground.
Tools for the job
For anything bigger than a small path, rent a plate compactor; hand tampers cannot match it. A wheelbarrow, shovels, a hard rake and stakes with string are the rest of the kit. Wet the stone lightly before compacting so it binds.
Measuring the area
Measure length and width in feet at a few points and use the largest figures, since real sites are rarely square. For odd shapes, split the area into rectangles and circles, work out each one and add them together. Depth is the number most people underestimate: drive a stake, run a level string and measure down to the dug-out surface in several spots.
Questions people ask
How many tons of river rock for an 18 ft circle?
About 3.2 tons at 3 inches deep.
How many square feet is an 18 foot circle?
About 254.5 square feet.
How many tons of river rock are in a cubic yard?
Roughly 1.35 tons for planning, but suppliers vary with stone size and moisture.
Should I put landscape fabric under the stone?
On soft or clay soil, a woven geotextile keeps stone from sinking into the dirt and makes the layer last longer.
Related guides
- Gravel for a Fire Pit Area: Best Types and Depth
- How Much Does a Ton of Gravel Cover? Depth Chart
- Tons to Cubic Yards for Gravel: Conversion Chart
- Crushed Stone vs Gravel: Differences and Best Uses
- Geotextile Fabric for Driveways: Woven vs Nonwoven and How Much You Need
- Compacting a Driveway Gravel Base in Lifts
- How Much Gravel for a 16 Foot Circle?
- How Much Pea Gravel for an 18 Foot Circle?
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