The math behind your estimate
The inputs, allowance, and rounding stay visible.
- Volume
- Volume = Length × Width × Depth, summed over all areas
- Allowance
- Order volume = Volume × (1 + allowance %)
- Weight
- Weight = Order volume × density (approximate)
Assumptions
- Densities are approximate reference values (e.g. mixed gravel ~105 lb/ft³ / 1,680 kg/m³). Actual density varies with stone type, gradation, and moisture — suppliers quote their own tons-per-yard figure.
- The default 5% allowance covers compaction and settling. Driveways and paths that will be compacted mechanically may need 10–15% extra.
- Depth matters more than it looks: going from 2 in to 3 in of coverage increases the order by 50%.
Frequently asked questions
- How deep should gravel be?
- Walkways and decorative cover: 2–3 inches. Driveways: 4–6 inches total, usually in two compacted layers of different stone sizes. Patio and slab bases: typically 4 inches of compacted base — check your project's spec.
- How many tons is a cubic yard of gravel?
- Roughly 1.4 tons per cubic yard for typical mixed gravel, but it genuinely varies from about 1.2 to 1.7 tons depending on stone type and moisture. Your supplier's own conversion is the number to order by.
- Why does my weight estimate differ from the quarry's quote?
- Density isn't a universal constant: crushed limestone, pea gravel, and river rock all weigh differently, and wet material weighs noticeably more than dry. This calculator's presets are approximations for planning, not invoices.
- Should I order extra gravel?
- Yes — gravel compacts and settles once spread and used. The default 5% allowance suits loose decorative cover; add 10–15% for surfaces that will be mechanically compacted, since compaction reduces the placed volume.
Sources
- Typical aggregate bulk densities (supplier reference values)