How to calculate gravel
Multiply length by width to find area, then multiply by depth. The calculator converts the result to cubic yards and multiplies it by a planning density to estimate tons.
Gravel formula
Cubic feet = length × width × (depth in inches ÷ 12). Cubic yards equal cubic feet ÷ 27; estimated tons equal cubic yards × density.
Worked example
A 30 × 10 foot area at 4 inches deep contains 100 cubic feet, or 3.70 cubic yards. At 1.4 tons per cubic yard, the planning weight is about 5.19 tons.
Practical tips
- Measure compacted finished depth, not loose delivery depth.
- Confirm base-layer and top-layer requirements for driveways.
- Ask the supplier for the actual material density and consider a small allowance for compaction and uneven grade.
Assumptions and limitations
The 1.4 tons/yd³ default is a general planning value. Actual weight varies substantially with stone type, grading, moisture, and compaction; supplier figures should control an order.
Frequently asked questions
How deep should gravel be?
Depth depends on the use, soil, aggregate, and whether a compacted base exists. Follow local or supplier guidance for structural projects.
Should I add extra gravel?
A modest allowance may cover compaction and low spots, but calculate it with your supplier because delivery is commonly sold by weight.