Estimate decomposed-granite volume from the dimensions you measure. Weight and cost are optional outputs and appear only when you enter a supplier-provided bulk density and your own price.
Calculate decomposed granite quantity
Important: this tool does not assume a universal density, compaction factor, waste rate or current price. Those vary by material, supplier and project, so they remain explicit user inputs.
What the result means
The core result is geometric volume. In US customary units the calculator reports cubic feet and cubic yards; in metric it reports cubic meters and liters. If you add a bulk density, the tool converts the adjusted volume to weight. If you also enter a price, it multiplies that user-supplied rate by the calculated weight.
Use the finished material depth you actually intend to place. This is a quantity estimate, not a recommendation for base preparation, compaction, drainage or installation depth.
Formula and unit method
For a rectangular area, volume is length × width × depth. The extra-material percentage is applied after base volume: adjusted volume = base volume × (1 + extra% ÷ 100). US cubic yards are calculated from cubic feet using 27 cubic feet per cubic yard. Metric volume uses meters directly.
If density is supplied, weight is volume × density. US short tons use 2,000 pounds per short ton; metric tonnes use 1,000 kilograms per tonne. The unit relationships follow NIST measurement tables.
Example without assuming density
A 12 ft × 20 ft area at 2 in depth contains 40 cubic feet, or about 1.48 cubic yards, before any extra-material allowance. If you choose 10% extra, the volume becomes about 44 cubic feet, or 1.63 cubic yards. Weight is intentionally not shown until you enter a density applicable to the material you are buying.
Inputs to verify before ordering
- Measure the actual length and width rather than relying on a nominal project size.
- Enter the finished depth as a project input; this calculator does not choose the depth for you.
- For weight, use the bulk density stated by the supplier or applicable product documentation.
- For price, enter the quote or rate you want to evaluate. No live market price is built into the page.
Questions about decomposed-granite quantity
Why does the calculator not include a default density?
Bulk density depends on the material and its condition. A fixed default could turn a transparent volume calculation into an unsupported weight claim, so weight stays optional until you provide a density.
Can I use the result as an order quantity?
Use it as a planning estimate, then compare it with the supplier’s ordering units, minimum quantities, density and delivery rules.
Does the tool choose compaction or installation depth?
No. It calculates the geometry and any extra percentage you enter. Project-specific preparation and installation decisions are outside this calculator.
Measurement source: NIST Handbook 133, Appendix E — General Tables of Units of Measurement.