Decorative Stone Calculator
Calculate exactly how many tons or cubic yards of river rock, crushed stone, or lava rock you need for your landscaping.
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Decorative Stone Beds
Calculate the length and width of the garden area you want to cover. A 2-inch depth of decorative stone is highly recommended for maximum weed control.
How to Use the Decorative Stone Calculator
Decorative rock is expensive. Using our calculator ensures you order the exact amount of tonnage you need to finish the job without wasting money on excess material.
- Select your stone type: Use the dropdown to select the type of rock you are using. This changes the density calculation (for example, lava rock is much lighter than marble).
- Measure your beds: Enter the length and width of your garden beds in feet.
- Set the depth: 2 inches is the standard depth for maximum weed suppression and visual appeal.
Landscape Stone Formula
We calculate the volume of your beds first, and then multiply by the specific density of the rock type you chose.
Step 1: Calculate Volume
Volume (ft³) = Length (ft) × Width (ft) × (Depth in inches ÷ 12)
Step 2: Convert to Tons
Tons = (Cubic Feet × Stone Density) ÷ 2000 lbs
Density Averages: Crushed Stone (105 lbs/cf), River Rock (100 lbs/cf), Lava Rock (50 lbs/cf), Marble (110 lbs/cf).
Stone Example Calculation
You want to fill a front garden bed that is 30 feet long and 5 feet wide with 2 inches of River Rock.
- Area: 30 × 5 = 150 square feet.
- Volume: 150 × (2/12) = 25 cubic feet.
- Tons (River Rock): (25 × 100) ÷ 2000 = 1.25 tons.
Conclusion: You need to order exactly 1.25 tons of river rock to get complete coverage.
Tips for Landscaping with Stone
- Install metal edging: Before pouring stone, install steel or aluminum landscape edging. This provides a hard boundary that prevents the stones from spilling out into your grass where they can damage your lawnmower.
- Wash the stone: Bulk decorative stone is usually covered in "stone dust" from the quarry. Once it is spread, give it a heavy spray with your garden hose. This washes the dust down into the soil and reveals the true, vibrant color of the rocks.
- Avoid trees: Avoid putting heavy rock directly over the root zones of delicate trees. The weight can compact the soil, and rocks absorb massive amounts of heat from the sun, which can bake shallow tree roots.
Frequently Asked Questions
How deep should decorative stone be?
For most garden beds and decorative landscaping areas, a depth of 2 inches is ideal. If you are using larger river rocks (2-3 inches in diameter), you may need a depth of 3 inches simply to ensure full coverage over the soil.
How much does a cubic yard of river rock weigh?
River rock is very dense. A single cubic yard of river rock weighs approximately 2,600 to 2,900 lbs (about 1.3 to 1.45 tons).
Is lava rock lighter than regular stone?
Yes, significantly. Lava rock is porous and full of air holes. A cubic yard of lava rock weighs only about 1,200 to 1,500 lbs, making it nearly half the weight of river rock or marble chips. This makes it much easier to haul and spread.
Should I use landscape fabric under the stone?
Absolutely. Without commercial-grade woven landscape fabric, weeds will quickly grow up through your expensive decorative stone, and the stones will gradually sink into the mud during heavy rains.