Quick Answer
- Minimum depth (light use): 4 inches of compacted gravel
- Standard residential driveway: 4–6 inch surface layer + 4–6 inch base = 8–12 inches total
- Heavy vehicle / truck use: 6 inch surface + 6–8 inch base = 12–14 inches total
- Soft/clay soil: Add geotextile fabric under base layer
Depth by Use Case
| Use Case | Surface Depth | Base Depth | Total Depth |
|---|---|---|---|
| Foot path / garden path | 2–3" | none | 2–3" |
| Light vehicle (sedan, SUV) | 4" | 4" | 8" |
| Standard residential driveway | 4–6" | 4–6" | 8–12" |
| Heavy trucks / RVs | 6" | 6–8" | 12–14" |
| Commercial / repeated heavy load | 6" | 8–12" | 14–18" |
The 3-Layer System
- Layer 1 — Subgrade: Native soil, graded and compacted. On clay soils, lay geotextile fabric to prevent migration.
- Layer 2 — Base course: 4–8" of #21A, #411, or crushed limestone. Large angular stones lock together under compaction.
- Layer 3 — Surface course: 4–6" of #57 crushed stone, pea gravel, or decomposed granite. This is what you see and drive on.
Never dump a single 12-inch layer of gravel. Layering allows each course to be compacted independently, which prevents rutting. Compact base before adding surface layer.
Adjusting for Soil Type
| Soil Type | Recommendation |
|---|---|
| Sandy / well-draining | Standard 8–12" total. No fabric needed. |
| Loam / mixed soil | Standard 8–12" total. Optional fabric. |
| Clay / poor drainage | Add 1–2" extra base + geotextile fabric |
| Soft/boggy ground | Use geogrid or sub-base drainage layer (consult an engineer) |
Calculate Cubic Yards by Depth
Cubic Yards = (Length ft × Width ft × Depth in) ÷ 324Example: 12 ft × 40 ft driveway at 6" depth:
12 × 40 × 6 ÷ 324 = 8.9 cubic yards
| Driveway Size | 4" Depth (yd³) | 6" Depth (yd³) | 12" Total (yd³) |
|---|---|---|---|
| 10×20 ft | 2.5 | 3.7 | 7.4 |
| 12×40 ft | 5.9 | 8.9 | 17.8 |
| 14×50 ft | 8.6 | 12.9 | 25.9 |
| 20×60 ft | 14.8 | 22.2 | 44.4 |
Calculate Gravel for Your Driveway
Enter length, width, and depth to get exact cubic yards and cost estimate.
Open Gravel Calculator →FAQ
Is 4 inches of gravel enough for a driveway?
4 inches is the minimum for a light-use driveway on good soil. For standard residential use, use 4–6 inches of surface gravel over a 4–6 inch base layer — 8–12 inches total is the standard.
Should I use gravel fabric under my driveway?
Yes — on clay or soft soils. Geotextile landscape fabric placed between the subgrade and base gravel prevents fines from migrating up into your gravel, extending the life of the driveway by 5–10 years.
How often should gravel driveways be topped up?
Plan to add 1–2 inches of fresh surface gravel every 3–5 years, or when ruts, potholes, or bare spots appear. Annual raking redistributes displaced gravel and can extend intervals.