Methodology
Every step of the estimate
The calculator works in SI internally, then displays the units useful for US and metric purchasing. No density, allowance, or compaction factor is silently added.
1. Parse measurements
Inputs accept positive decimal numbers, simple fractions, or mixed fractions. Thousands separators are accepted. Missing values, zero dimensions, negative values, malformed fractions, and non-finite results stop calculation and hide the previous result.
2. Calculate area
- Rectangle: length × width
- Circle: π × (diameter ÷ 2)²
- Known area: entered area
Non-overlapping areas are summed. The shared project depth is then applied to each region unless a visible region override is entered.
3. Calculate loose order volume
Loose volume = Σ (region area × region depth) × compaction factor × (1 + allowance ÷ 100)
Each blank region override inherits the shared depth. The factor is 1 when depth describes loose placed material. When depth describes a finished compacted layer, the factor must be entered from the supplier and must be at least 1. Allowance defaults to 0% and is applied once after compaction.
4. Estimate weight as a range
Weight range = loose volume × [minimum density, maximum density]
The prefilled 1.4–1.7 short tons/yd³ range is an illustrative planning assumption supplied for this tool, not a universal or tested density range for gravel. Replace it with the loose bulk density of the exact product. Supplier guidance confirms aggregate densities vary by material and calculator outputs are estimates.
5. Apply purchasing rules
For a bulk quote, GravelSum converts the required volume or weight to the quoted unit, compares it with the supplier minimum, then rounds up to the entered increment. Cost equals rounded quantity × unit price + entered delivery. For bags, required amount is divided by bag size and rounded up to a whole bag. When weight is density-dependent, quantities and costs remain ranges.
Conversions
| From | To |
|---|---|
| 1 ft | 0.3048 m |
| 1 in | 0.0254 m |
| 1 yd³ | 0.764554857984 m³ |
| 1 short ton | 907.18474 kg |
Sources and limits
Unit conversions are traceable to NIST metric and SI resources and NIST SP 811 Appendix B.8. The density warning is supported by Mulzer Crushed Stone’s aggregate calculator, which states that densities vary between materials and calculations are estimates.
Floating-point arithmetic can introduce negligible display rounding. Displayed values are rounded for readability; ordering rounds only as described above. The estimate does not replace product documentation, a site assessment, or supplier confirmation.