Landscape Rock Calculator
Estimate decorative rock volume and short tons for a landscape bed. Enter bed depth and material bulk density to compare volume-based and weight-based orders.
How the result changes
Only bed length changes; all other inputs stay at your current values. The line illustrates the formula across the shown range. This is not a forecast of real-world outcomes.
About this calculation
Landscape rock is commonly sold by cubic yard or by weight, while the bed is measured in feet and inches. This calculator bridges those units using the depth you intend to cover and the bulk density of your chosen material. Calculate landscape rock when ordering building materials.
Formula
cubic yards = length × width × depth in feet ÷ 27; short tons = cubic feet × density ÷ 2,000
Worked example
With Bed length: 24 ft, Average bed width: 4 ft, Rock depth: 3 in, Bulk density: 100 lb/ft³, rock volume is 0.888889 yd³.
Inputs and units
Enter a rectangular bed's length and average width in feet. Convert the target settled layer depth from inches automatically with this form, and provide a bulk density in pounds per cubic foot if you need the weight estimate.
- Bed length (ft): Measure the longest straight length of the rock-covered bed.
- Average bed width (ft): Use an average width for tapered beds or split the bed into rectangles.
- Rock depth (in): Measure the settled depth in inches, not the height of individual stones.
- Bulk density (lb/ft³): Use a bulk weight for the selected stone and void space; the default is illustrative.
Calculation and worked example
The bed's square feet multiplied by depth divided by 12 gives cubic feet. Divide by 27 for cubic yards. For US short tons, multiply cubic feet by the entered pounds per cubic foot and divide by 2,000 In compact notation, cubic yards = length × width × depth in feet ÷ 27; short tons = cubic feet × density ÷ 2,000.
A 24 ft by 4 ft bed has 96 ft² of surface. A 3 in layer is 0.25 ft deep, so it needs 24 ft³ or about 0.889 yd³. At 100 lb/ft³, the theoretical weight is 2,400 lb, or 1.2 short tons.
How to use the answer
The volume is usually the better number when a yard-based supplier quotes loose landscape rock. The short-ton result is density-dependent; two products can cover the same volume but weigh differently because of stone type and voids.
For curved garden strips, break the outline into approximate rectangles and add their volumes. If a tree circle has a different depth, calculate it separately rather than increasing the depth across every bed.
Assumptions and checks
This model assumes uniform coverage and a rectangular footprint. It does not subtract planting holes or include settlement, delivery loss, or extra material used to blend edges into surrounding soil.
Entering 3 inches as 3 feet makes volume twelve times too large. Also distinguish US short tons of 2,000 pounds from metric tonnes; a supplier invoice may use either word with a different unit definition.
A one-square-foot patch at one inch depth uses one-twelfth of a cubic foot. Scale that simple patch to the bed's area before dividing by 27, and compare the result with the order unit shown by the supplier.
Common questions
What does the rock volume result represent?
The first result is the geometric volume of the chosen rock layer in cubic yards, before any extra quantity for settling or irregular placement.
What should I check before relying on this result?
Confirm average width, intended settled depth, and the material's loose bulk density. Ask whether the seller prices by cubic yard or US short ton.
Inputs
- Bed length (ft)
- Average bed width (ft)
- Rock depth (in)
- Bulk density (lb/ft³)