How the landscape rock calculator works
Landscape rock is usually planned by volume. To calculate landscape rock for a rectangular bed, you need the length, width, and average depth of the area. This calculator converts those measurements into cubic feet and then into cubic yards so you have a practical volume estimate for planning an order.
Landscape rock calculator formula
Volume
cubic feet = length × width × depth in feet
cubic yards = cubic feet ÷ 27
order amount = cubic yards × (1 + waste ÷ 100)
Example
A 20 ft × 10 ft landscape bed with an average rock depth of 3 inches is about 1.85 cubic yards before an allowance.
With a 10% allowance, the estimate is about 2.04 cubic yards.
How much rock do I need for landscaping?
The amount depends on the area you are covering and the depth you want. If you want to calculate rock for landscaping, measure each section separately when the shape is irregular and add the volumes together. Use an average depth rather than a single spot that happens to be deeper or shallower.
Planning your rock order
Different landscape materials have different densities, sizes, and coverage rates. This calculator estimates volume, not the exact weight of a particular stone. If your supplier sells the material by the ton or gives a coverage rate for a specific product, compare this volume estimate with the supplier's product information before placing the order.
Frequently asked questions
How do I calculate landscaping rock?
Measure the length and width of the area, choose an average depth, convert the depth from inches to feet, and calculate the volume. This landscaping rock calculator then converts the result to cubic yards and can add a waste allowance.
What depth should I use for landscape rock?
The right depth depends on the type of rock, the area, and how you want the finished surface to look. Use the depth recommended for your material rather than assuming one depth works for every project.
Should I add extra rock?
A modest allowance can help with uneven areas, measuring differences, and material left over during placement. The appropriate allowance depends on the shape and condition of the site.
Can I calculate rock for an irregular garden bed?
Yes. Divide the bed into smaller rectangles or other simple sections, calculate each section separately, and add the volumes together before converting the total to cubic yards.
Does this calculator tell me how many tons of rock I need?
No. It gives a volume estimate in cubic yards. Rock weight varies by material and size, so use the supplier's coverage or weight information when converting the volume into tons.