Quick answer
A new gravel driveway on native soil is usually built 8 to 12 inches thick in three layers: about 4 to 6 inches of large #3 stone (or similar) for the base, about 4 inches of #57 stone or crusher run in the middle, and 2 to 4 inches of crusher run or a finer stone on top. Refreshing an existing driveway with a sound base usually takes only 2 to 4 inches of new top stone.
What the stone numbers mean
Numbers like #3 and #57 come from standard aggregate gradations used by state transportation departments. A smaller number means larger stone. Exact sizes vary slightly by state and quarry, so ask your supplier what they stock.
| Stone | Approximate size | What it is | Driveway use |
|---|---|---|---|
| #3 | about 1 to 2 in | Clean crushed stone, no fines | Bottom layer; bridges soft soil and drains |
| #57 | about 1/2 to 1 in | Clean crushed stone, no fines | Middle layer or top layer; drains well |
| Crusher run | 3/4 in down to dust | Crushed stone mixed with stone dust; also called dense grade, 3/4 minus, or #411 in some areas | Top layer; packs hard and smooth |
| #8 | about 3/8 to 1/2 in | Small clean stone | Decorative top dressing |
The key difference is fines. Clean stone (#3, #57) has no dust, so water drains through it but the pieces can roll. Crusher run contains dust that fills gaps and binds when compacted, giving a firm surface that sheds water.
What each layer does
Base layer: 4 to 6 inches
Large angular stone spreads the weight of vehicles over the soil and creates a drainage layer. On soft or clay soil, some builders use even larger stone (#1 or #2, often 2 to 4 inches) or go deeper. A woven geotextile fabric under this layer helps keep stone from sinking into mud over time.
Middle layer: about 4 inches
#57 stone or crusher run fills the large gaps at the top of the base layer and gives a more even surface. Many residential driveways combine the middle and top layers into one 4 to 6 inch crusher run layer.
Top layer: 2 to 4 inches
Crusher run makes the firmest surface. Clean #57 or a smaller decorative stone looks nicer and drains better but shifts under tires and needs raking. Avoid rounded pea gravel on slopes; it rolls and ruts.
Step by step
- Call 811 to mark utilities before digging.
- Mark the driveway. A single car lane is usually 10 to 12 ft wide.
- Excavate. Strip sod and topsoil, usually 8 to 12 inches, down to firm subsoil. Organic topsoil compresses and should not stay under the stone.
- Shape for drainage. Crown the center or slope the surface to one side by about 2 percent (1/4 inch per foot) so water runs off instead of pooling. Make sure ditches or the lawn edge can take the runoff.
- Compact the soil and lay fabric if used.
- Spread and compact each layer. Lay stone in lifts of about 4 inches and compact each with a plate compactor or roller before adding the next.
- Finish the top. Spread crusher run, wet it lightly and compact. The dust binds as it dries.
How much stone you need
Cubic yards = length x width x depth in inches / 12 / 27. Crushed stone weighs about 1.4 to 1.5 tons per cubic yard loose; compacted crusher run is heavier, so suppliers may quote more tons per yard for it. Order about 10 to 15 percent extra for compaction and edges.
Example: a 60 ft by 12 ft driveway is 720 sq ft.
| Layer | Depth | Cubic yards | Tons (about 1.4/yd) |
|---|---|---|---|
| #3 base | 4 in | 8.9 | 12.4 |
| #57 middle | 4 in | 8.9 | 12.4 |
| Crusher run top | 3 in | 6.7 | 9.3 |
That is roughly 34 tons before the extra allowance, or two to three dump truck loads depending on truck size. The gravel calculator handles each layer and lets you enter a price per ton.
Maintenance
- Rake or drag the surface once or twice a year to fill ruts and move stone back to the center.
- Add 1 to 2 inches of top stone every few years as it wears and sinks.
- Fix low spots quickly. Standing water softens the base and makes potholes grow.
- Keep ditches and culverts clear so water does not run down the driveway.
Common questions
Can I just use crusher run for the whole thing?
On firm, well-drained soil with light traffic, 6 to 8 inches of compacted crusher run often works. On clay or wet ground, a layer of large clean stone underneath holds up much better.
Is #57 stone good for the top?
It drains and looks clean, but it does not lock together, so it can feel loose and spread over time. Crusher run is firmer for daily driving.
For decorative stone around the driveway edge, see the river rock calculator.