Gravel driveway guide: layers, depth and how much to order
A gravel driveway that lasts is built in layers, each doing a different job. Here's how the layers work and how to size your stone order.
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Why layers matter
A single thick layer of pretty stone on bare soil turns into ruts and mud within a season. The load of a car has to be spread down to the ground below, and water has to get out. That's the job of the lower layers; the top layer is just the wearing surface.
A typical layered driveway
| Layer | Common material | Typical compacted depth | Job |
|---|---|---|---|
| Subgrade | Existing soil, stripped of topsoil and roots | — | Firm, graded, crowned or sloped to drain |
| Base | Large crushed stone (such as #3) or crusher run | 4–6 in | Spreads the load and bridges soft spots |
| Middle | Medium crushed stone (such as #57) | 3–4 in | Locks into the base, drains |
| Surface | Crusher run / #411 or a decorative stone | 2–3 in | Packs into a firm driving surface |
Stone sizes are named differently from region to region, and many local quarries sell their own driveway blends. Tell the supplier what the layer is for and ask what they recommend. On firm, well-drained soil with light traffic, a base of road base (crusher run) topped with surface stone can be enough; on clay or soft ground, go deeper and consider a stabilization fabric between the soil and the stone.
How much stone to order
Work out each layer separately — they're usually different materials at different prices.
Example: a 12 × 60 ft driveway (720 sq ft)
- Base, 4 in: 720 × 4 ÷ 12 ÷ 27 = 8.9 yd³ → +10% = 9.8 yd³ ≈ 14 tons
- Middle, 3 in: 6.7 yd³ → +10% = 7.3 yd³ ≈ 10 tons
- Surface, 2 in: 4.4 yd³ → +10% = 4.9 yd³ ≈ 7 tons
- Total: roughly 31 tons of stone — several truckloads, so plan where the trucks will dump.
Use the gravel calculator for each layer and change the density to your supplier's figure.
Width, crown and drainage
- Width: about 10 to 12 feet for a single lane, with extra width at curves and turnarounds.
- Crown: build the surface slightly higher in the middle so water runs off both sides rather than down the tire tracks.
- Ditches and culverts: water is the main enemy. Give it somewhere to go along the edges and under the drive where it crosses a low spot.
- Edging: a border of timber, steel or larger stone keeps gravel from spreading into the lawn.
Building it
- Strip the topsoil and organic material; it compresses and holds water.
- Grade and compact the subgrade with the crown or cross-slope you want.
- Lay fabric on soft or clay soils if your supplier recommends it.
- Spread and compact each layer in lifts of a few inches, dampening it slightly so it compacts well. A plate compactor handles small drives; rent a roller for long ones.
- Top up the surface layer as it wears — a light top-dressing every few years keeps it firm.
Gravel or asphalt?
Gravel costs less to build and drains naturally, but it needs periodic raking and topping up and can be dusty. Asphalt costs more up front but is smoother and easier to clear of snow. A well-built gravel base is also the first stage of an asphalt driveway, so you can pave later — see the asphalt calculator for tonnage.
Frequently asked questions
How deep should a gravel driveway be?
Commonly 8 to 12 inches in total across the layers, and more on soft ground. A top-up of an existing driveway is usually 2 to 3 inches.
What's the best gravel for the top layer?
An angular stone with fines — crusher run or #411 — packs into a hard surface. Round pea gravel looks nice but shifts under tires.
How many tons of gravel per 100 feet of driveway?
For a 12 ft wide driveway, each inch of depth over 100 feet is about 3.7 yd³ — roughly 5.2 to 5.6 tons of crushed stone before extra for compaction.