Methodology
How every estimate is produced
The calculator normalizes the entered measurements, computes geometric volume, applies a bulk density, and then adds the selected order allowance. No result is hidden behind a proprietary formula.
Volume = area × finished depth
Weight = volume × bulk density
Order = calculated quantity × (1 + extra %)
Unit conversion
Internally, the calculator converts measurements to meters, square meters, cubic meters, and kilograms. It then displays the result in the unit system you selected. This avoids mixing inches, feet, and yards inside one formula.
Density assumptions
Material presets are rounded planning values, not product specifications. The custom density field exists because bulk density varies with gradation, particle shape, moisture, and compaction state.
Cost assumptions
Cost equals the calculated order quantity times the price you enter, plus an optional fixed delivery amount. Labor, equipment, tax, excavation, disposal, and project-specific work are outside the estimate.
Scope and review
Content is written to explain the arithmetic and the practical limits of material estimating. Pages are reviewed when the calculator, assumptions, or site structure changes. The current site review date is August 31, 2026.