How Much Gravel Do I Need for a Driveway?
A driveway is layers, not a depth
The most common mistake is ordering "4 inches of gravel" for a driveway. One layer of uniform stone on soil ruts and sinks within a season, because nothing locks it together and nothing spreads the load.
| Layer | Depth | Material | Job |
|---|---|---|---|
| Sub-base | 4–6 in | #3 or #4 stone (2–3 in rock) | Spreads load, drains, keeps the driveway off the subsoil |
| Base | 4 in | Crusher run / quarry process | Fines lock together under compaction into a solid layer |
| Top | 3–4 in | #57 stone or decorative | Driving surface, sheds water, replaceable |
Total 11–14 in for a driveway carrying cars over normal soil. On firm, well-draining ground you can sometimes drop the sub-base and run 4 in of crusher run plus 3 in of #57. On soft clay you may need geotextile fabric under the sub-base — cheap, and it stops stone migrating down into the mud where it does nothing.
Worked example: 40 x 10 ft driveway
| Layer | Depth | Cu ft | Cu yd | Tons |
|---|---|---|---|---|
| Sub-base #3 | 5 in | 167 | 6.2 | 8.7 |
| Base crusher run | 4 in | 133 | 4.9 | 7.4 |
| Top #57 | 3 in | 100 | 3.7 | 5.2 |
| Total | 12 in | 400 | 14.8 | 21.3 |
Before the compaction allowance. Add 15–20% to the crusher run layer, which loses that much volume when tamped.
Twenty-one tons for a small driveway surprises most people. It is also why the gravel calculator puts tons in the headline: your quarry quotes and invoices by the ton, and a single dump truck carries roughly 15–20 tons.
Compact in lifts
Gravel deeper than 2–3 in will not compact through its depth in one pass. Spread and tamp in layers with a plate compactor or roller, wetting crusher run lightly as you go — the fines need moisture to bind. A driveway that feels solid on top but was placed in one 8 in dump is still loose underneath and will rut.
Crown it and edge it
- Crown the surface about 2% from centre to edge so water runs off rather than sitting and washing fines out of the base.
- Edge it with timber, steel or a soil shoulder. Unedged gravel migrates sideways into the lawn, and you lose an inch of depth a year to spreading.
- Plan for top-up. A gravel driveway needs 1–2 in of new top stone every few years. That is maintenance, not failure.
Choosing the top stone
Angular crushed stone such as #57 locks together and stays put. Rounded pea gravel and river rock look better and behave worse: they roll underfoot, migrate under tyres, and end up in the road. If you want the look of rounded stone, use it in a border or a walkway, not on the drive.
Gravel is quoted by the ton but measured by volume. Enter the area and depth to get both — plus a compaction allowance, because crusher run settles and the loose volume you order is not the compacted depth you end up with.
Frequently asked questions
How many tons of gravel for a 40x10 driveway?
About 21 tons for a full three-layer build at 12 inches total depth — roughly 8.7 tons of sub-base, 7.4 of crusher run and 5.2 of #57 top stone. A single-layer 4 inch top-up on an existing base is only about 7 tons.
How deep should a gravel driveway be?
Eight to twelve inches in total, built in layers: 4 to 6 inches of coarse sub-base, 4 inches of compacted crusher run, and 3 to 4 inches of #57 or decorative top stone. One uniform layer of the same stone will rut.
What kind of gravel is best for a driveway?
Angular crushed stone. Crusher run for the base because its fines compact into a solid layer, and #57 crushed stone on top because the angular faces lock together. Avoid pea gravel and river rock on a driving surface — rounded stone rolls and migrates.
Do I need fabric under a gravel driveway?
Over soft or clay soil, yes. Geotextile fabric stops stone being pushed down into the subsoil and stops mud pumping up into the stone. It is inexpensive relative to losing several inches of base into the ground.