Landscape Rock Calculator
Calculate tons of decorative landscape rock needed for a bed at your depth, using a 1.4 tons per cubic yard density, plus cost.
How this calculator works
Landscape rock is sold by the ton like other bulk stone, so this calculator converts your bed’s area and depth into cubic yards, then multiplies by a typical decorative-stone density of 1.4 tons per cubic yard to get the tons you need to order.
Formula: Cubic yards = (Length ft × Width ft × Depth ft) ÷ 27. Tons = Cubic yards × 1.4.
Worked example
A 15 ft × 10 ft decorative bed at a 2-inch depth:
- Depth in feet: 2 ÷ 12 = 0.167 ft
- Cubic yards: (15 × 10 × 0.167) ÷ 27 ≈ 0.926 yd³
- Tons: 0.926 × 1.4 ≈ 1.30 tons
- At $75/ton, that’s $97.22 before waste.
Coverage reference
| Depth | Coverage per ton |
|---|---|
| 1 in | ~231 sq ft |
| 2 in | ~116 sq ft |
| 3 in | ~77 sq ft |
How to measure your bed
Measure the bed’s length and width along the ground where fabric will be laid, not around individual plants, and use 2 inches as your depth unless the rock size or design calls for deeper coverage. For beds with curved edges, treat the shape as a rough rectangle or split it into smaller rectangular sections and total the tons.
Frequently asked questions
What counts as landscape rock?
Landscape rock is a broad category covering decorative stone used for beds and borders — river rock, lava rock, cobble, and other larger ornamental stone sold by appearance rather than structural performance. This calculator uses a general 1.4 tons per cubic yard density typical of mixed decorative stone.
Why is landscape rock priced higher than plain gravel?
You're paying for appearance and consistency, not just volume — landscape rock is typically sorted by color, shape, or size for a specific decorative look, which costs more to source and process than utility gravel dug and crushed for structural use.
How deep should a landscape rock bed be?
2 inches is standard for most decorative beds over landscape fabric — enough to fully hide the fabric and suppress weeds without excess material cost. Larger accent stone or drainage-focused beds sometimes run deeper, 3-4 inches.
Do I need fabric under landscape rock?
Yes, in nearly every case. Without a fabric barrier, decorative rock gradually sinks into the soil and weeds grow up through the gaps, both of which undo the low-maintenance appeal that's the main reason to choose rock over mulch.
How does landscape rock compare to mulch on cost over time?
Landscape rock costs more upfront but doesn't need annual replenishing like mulch, which breaks down and needs topping off most years. Over a 5-10 year span, rock beds are often cheaper in total cost despite the higher initial price per ton.
Can I mix different sizes of landscape rock in one bed?
Yes, layering a smaller decorative rock with occasional larger accent stones is a common design approach, but calculate each size separately since larger accent pieces typically sit at a different effective depth than a uniform ground-cover layer.
Estimates only. Verify quantities with your supplier before purchasing.