Calculators for this guide
Why layers matter
Large stones lock together into a strong, free-draining foundation but are uncomfortable to drive on. Small stones give a smooth surface but wash away and rut without support underneath. Layering coarse to fine gives you both: strength at the bottom, a firm surface on top.
The three layers
| Layer | Typical material | Typical depth |
|---|---|---|
| Base | Large crushed stone (roughly 2–3 in pieces) | 4–6 in |
| Middle | Medium crushed stone (around ¾ in) | 3–4 in |
| Top | Fine crushed stone with fines, or decorative gravel | 2–3 in |
Total depth for a new driveway is typically around 8–12 in, depending on soil and traffic. Stone names vary by region and quarry, so describe the size and job to your supplier.
Calculating each layer
Calculate every layer separately, because each has its own depth and density. For a driveway 50 ft long and 12 ft wide (600 sq ft):
| Layer | Depth | Cubic yards | Tons (at ~1.4 t/yd³) |
|---|---|---|---|
| Base | 5 in | 9.26 | 12.96 |
| Middle | 3 in | 5.56 | 7.78 |
| Top | 2 in | 3.70 | 5.19 |
Add around 10% for compaction. Crushed stone settles noticeably under a plate compactor or roller.
Build tips
- Strip topsoil and grass down to firm subsoil, and grade the bed so water runs off to the sides.
- Lay a woven geotextile fabric over soft soil to keep stone from sinking.
- Compact each layer before adding the next — never dump all the stone at once.
- Crown the surface slightly (higher in the middle) so rain drains off instead of pooling.
- Edge the driveway with timber, steel or a low wall to stop gravel spreading.