Landscaping
Landscape Rock Calculator
Plan river rock and decorative stone for beds, borders and dry creek beds. This landscape rock calculator turns your measurements and depth into tons and cubic yards, shows how much area a ton of your chosen rock covers, and counts bags for small areas, with an optional cost.
Result
Enter your measurements and press Calculate. What to buy, the working and the cost will appear here.
How to use the landscape rock calculator
- Measure each bed or border as a rectangle or circle, or enter its area. Add a row per area.
- Choose a depth to suit the stone size. Rock needs to be deep enough to cover the fabric underneath with no gaps: roughly twice the size of the stones.
- Pick the rock. River rock and crushed stone weigh about 1.35 tons per yard; lava rock less than half that.
- Add a price per ton, per yard or per bag and press Calculate.
How much landscape rock do I need?
cubic yards = area (ft²) × depth (in) ÷ 324
tons = cubic yards × tons per cubic yard
A 100 ft² bed covered 3 inches deep needs 100 × 3 ÷ 324 = 0.93 cubic yards, or about 1.25 tons of river rock.
Worked example: a river rock border
A 30 ft × 3 ft border along a driveway gets 3 inches of 1–3 inch river rock, with 5% extra, at $120 per ton:
- Area 1: 30 ft × 3 ft = 90 ft²; × 3 in (0.25 ft) = 22.5 ft³
- With allowance: 0.833 yd³ × 1.05 = 0.875 yd³
- Weight: 0.875 yd³ × 1.35 tons/yd³ = 1.18 tons
- Bags: 23.63 ft³ ÷ 0.5 ft³ per bag = 48 bags
You need 1.18 tons (0.88 yd³). Ordered by the half ton that is 1.5 tons for about $180.00. Open this example in the calculator.
How deep should landscape rock be?
| Stone size | Typical depth |
|---|---|
| Pea-size and ⅜ in decorative stone | 2 in |
| ¾ in crushed or decorative stone | 2–3 in |
| 1–3 in river rock | 3–4 in |
| 3–5 in river rock and cobbles | 4–6 in, or a single layer set by hand |
| Decomposed granite paths | 3–4 in, compacted in layers |
How much does a ton of rock cover?
For river rock and other stone at about 1.35 tons per cubic yard:
| Depth | One ton covers | One cubic yard covers | One 0.5 ft³ bag covers |
|---|---|---|---|
| 2 in | 120 ft² | 162 ft² | 3 ft² |
| 3 in | 80 ft² | 108 ft² | 2 ft² |
| 4 in | 60 ft² | 81 ft² | 1.5 ft² |
| 5 in | 48 ft² | 65 ft² | 1.2 ft² |
Lava rock is so light that a ton covers more than twice the area. Always check whether a price is per ton or per cubic yard before comparing stones.
Decorative rock weights
| Rock | Per cubic yard | Notes |
|---|---|---|
| River rock (1–3 in) | 1.35 tons2,700 lb | Smooth rounded stone for beds, borders and dry creek beds. |
| Decorative crushed stone (3/8–3/4 in) | 1.35 tons2,700 lb | Small colored or crushed stone for beds and walkways. |
| Decomposed granite | 1.4 tons2,800 lb | Fine crushed granite for paths and patios; compacts firmly when wet and rolled. |
| Lava rock | 0.6 tons1,200 lb | Very light and porous, so a ton covers far more area than other stone. |
For driveway, drainage or base stone, use the gravel calculator, which includes road base and compaction.
Buying landscape rock
- Lay landscape fabric first to stop weeds and to keep rock from sinking into the soil.
- Edging (metal, stone or plastic) keeps rock out of the lawn and stops it migrating.
- Bulk vs bags: bagged decorative stone is convenient for small accents, but bulk is far cheaper by the ton. Rock is heavy: a half ton is about the limit for many pickups.
- See it in person. Color and size vary a lot between quarries, and photos rarely do it justice. Wet a stone to see its color after rain.
Assumptions and limitations
- Weights are typical loose figures; they vary with stone type and size.
- Depth is treated as even. Large rock placed by hand in a single layer covers differently; estimate by count instead.
- The allowance covers spillage and uneven ground; decorative rock barely compacts.
Landscape rock questions
How much area does a ton of river rock cover?
About 80 ft² at 3 inches deep and 60 ft² at 4 inches, for river rock weighing around 1.35 tons per cubic yard.
How many tons of rock do I need?
Multiply the area in square feet by the depth in inches, divide by 324 for cubic yards, then multiply by about 1.35 for tons. A 200 ft² bed at 3 inches needs about 1.85 cubic yards, or 2.5 tons.
Is landscape rock better than mulch?
Rock lasts for years and does not blow away or rot, but it heats up in the sun, does not feed the soil, and is hard to remove later. Mulch suits planting beds; rock suits borders, slopes and low-water designs. The mulch calculator estimates the alternative.
How many bags of river rock make a yard?
54 bags of 0.5 cubic feet. For more than about half a yard, bulk rock is usually much cheaper.
Formulas, unit conversions and default values are explained on our methodology page. Results are estimates; check manufacturer data and local codes before you buy or build.