Why Accurate Gravel Estimation Matters
Whether you're laying a gravel driveway, filling a drainage trench, or creating a decorative garden path, buying the right amount of gravel saves you money and avoids costly return trips to the quarry. Gravel is sold by the ton or cubic yard, and the two units do not convert identically — the weight depends on the type of stone. This guide walks you through the complete calculation process so you order exactly what you need.
The Core Formula: Length × Width × Depth
Gravel volume is calculated in cubic yards. All measurements must be in feet before you begin:
- Convert depth to feet: Divide inches by 12. A 4-inch depth =
4 / 12 = 0.333 ft. - Calculate cubic feet:
Length (ft) × Width (ft) × Depth (ft). For a 50 ft × 12 ft driveway at 4 inches deep:50 × 12 × 0.333 = 200 cubic feet. - Convert to cubic yards: Divide by 27.
200 / 27 = 7.4 cubic yards. - Add a 10% waste factor for settling and compaction:
7.4 × 1.10 = 8.14 cubic yards.
Recommended Gravel Depths by Application
| Application | Recommended Depth | Notes |
|---|---|---|
| Foot-traffic path | 2–3 inches | Pea gravel or decomposed granite |
| Decorative garden bed | 2–3 inches | River rock or colored gravel |
| Residential driveway (base) | 4–6 inches | #57 crushed stone or dense grade |
| Heavy-vehicle driveway | 6–8 inches | Compacted road base with top-dressing |
| French drain trench | Fill full trench | #57 or washed crushed stone |
Cubic Yards to Tons Conversion
Gravel quarries often sell by weight (tons). The conversion depends on the stone type:
| Gravel Type | Weight per Cubic Yard | Multiply Cubic Yards by |
|---|---|---|
| Pea Gravel (dry) | ~1.4 tons | 1.4 |
| #57 Crushed Limestone | ~1.5 tons | 1.5 |
| Crushed Granite | ~1.55 tons | 1.55 |
| River Rock | ~1.35 tons | 1.35 |
| Dense Grade (Road Base) | ~1.65 tons | 1.65 |
Average Gravel Cost per Ton (2024–2025)
Gravel prices vary by region and stone type. These are national average ranges:
- Pea Gravel: $25–$55 per ton delivered
- #57 Crushed Stone: $30–$65 per ton
- Road Base / Dense Grade: $18–$40 per ton
- River Rock (decorative): $45–$120 per ton
- Lava Rock: $80–$200 per ton
For most residential driveways (400–800 sq ft at 4 inches deep), expect to spend $300–$900 in materials, plus $50–$150 per hour for delivery and spreading if using a contractor.
Gravel Driveway Layers: Base, Middle, and Top
A professional gravel driveway is not one uniform layer. It is built in three compacted layers for stability, drainage, and longevity:
- Bottom Layer (#3 stone, 4 inches): Large 1–2 inch stones that lock into the soil and provide a drainage foundation. Never skips this step on clay-heavy soil.
- Middle Layer (#57 stone, 4 inches): Medium crushed stone that fills gaps and provides the structural base. Compact with a plate compactor.
- Top Layer (pea gravel or #9 chip, 2 inches): The decorative, driveable surface. Use angular (crushed) stone rather than round river rock — angular stone compacts and stays in place better.
Use our free Gravel Calculator to automatically compute the cubic yards, tons, and estimated cost for each layer of your project.