Gravel & Aggregate
How to Calculate Gravel for a Driveway
Estimate gravel for a driveway layer by layer: base, middle, and surface courses, tons per 100 feet, truckload planning, and a complete worked example with costs.
A gravel driveway is not one material - it's a three-layer pavement, and each layer uses a different stone size, a different density, and its own quantity calculation. Estimating it as a single lump of "gravel" is why so many driveways get one thin layer that vanishes into the mud by spring.
The three-layer takeoff
| Layer | Material | Compacted depth | Density (t/yd³) |
|---|---|---|---|
| Base course | #3 stone (2–4 in clean) | 4 in | 1.30 |
| Middle course | #57 stone (3/4–1 in) | 4 in | 1.35 |
| Surface course | Crusher run / dense-graded | 3 in | 1.45 |
(Regional names vary - describe the size and purpose to your quarry and they'll match the local product. Why three layers and what each does: Gravel Driveway Layers Explained.)
Worked example: new 100 × 12 ft driveway
Formula per layer: 100 × 12 × (depth÷12) ÷ 27 × 1.15 compaction × 1.05 waste.
- Base (4 in #3): 100×12×0.333÷27 = 14.8 yd³ → ×1.21 = 17.9 yd³ → ×1.30 = 23.3 tons
- Middle (4 in #57): same volume → 17.9 yd³ → ×1.35 = ~24 tons… but #57 compacts less; using ×1.10 compaction: 17.1 yd³ → 23.1 tons
- Surface (3 in crusher run): 11.1 yd³ → ×1.21 = 13.4 yd³ → ×1.45 = 19.5 tons
Wait - that totals ~66 tons, more than the quick answer above. The difference: many builders use 3-in base and middle lifts on firm, well-draining subgrades (3+3+3), which lands the total near 45 tons. On soft ground, build thicker; on good ground, 3-in lifts are common. Depth decisions dominate cost, so probe your subgrade (a rod pushed into wet-season soil tells you a lot) before choosing.
Quick per-100-ft reference (12 ft wide, compacted)
| Build | Total depth | Tons per 100 ft | Truckloads |
|---|---|---|---|
| Surface refresh only | 3 in | 14–16 | 1 |
| Light rebuild (firm soil) | 3+3+3 = 9 in | 42–46 | 3 |
| Full build (soft soil) | 4+4+3 = 11 in | 60–66 | 4–5 |
Run each layer through the calculator with its own depth and material - three quick passes gives the full order.
Open the Gravel CalculatorDon't skip these quantity add-ons
Geotextile fabric: driveway area plus 5% for laps - a 100×12 driveway needs ~1,260 ft². On any soil that's soft when wet, fabric pays for itself by keeping the base from disappearing downward.
Crown allowance: the finished surface should crown 2–4% from centerline to edges to shed water. Building the crown consumes roughly 3–5% extra surface material.
Culverts and edges: if the driveway crosses a swale, budget the culvert pipe and its stone bedding separately.
Delivery planning
A tandem truck hauls 13–15 tons legally. Plan dump locations before trucks arrive: base stone dumped in piles along the run beats one mountain at the street, and each layer must be spread and compacted before the next arrives. Multi-load orders often get better per-ton pricing - ask.
When to call a professional
Driveways on steep grades (over ~10%), crossing drainage paths, on expansive clay, or serving heavy vehicles benefit from contractor experience with subgrade prep and compaction equipment. If the ground pumps under a loaded truck, no amount of stone fixes it - that's a geotechnical problem.
Frequently Asked Questions
How much gravel do I need for a 100-foot driveway?
A 100 x 12 ft driveway built properly (4 in base + 4 in middle + 3 in surface, compacted) needs roughly 42-46 tons across all three layers. A 3-inch refresh of the surface alone needs about 14-16 tons.
How many inches of gravel does a driveway need?
8-12 inches total for a new driveway on decent soil, built as three compacted layers. A single thin layer disappears into the subgrade within a couple of seasons.
What size gravel is best for a driveway surface?
A dense-graded product with fines - often called crusher run, road base, or #411/#21A depending on region - locks together under traffic. Clean rounded stone rolls and ruts.
How many tons of gravel fit in a dump truck?
Tandem-axle dump trucks legally haul 13-15 tons of gravel. A 45-ton driveway project means about three truckloads - ask about multi-load pricing.
How much does a gravel driveway cost per foot?
With material at $25-45/ton delivered, a properly built 12-ft-wide driveway runs roughly $10-20 per linear foot in materials, plus fabric (~$0.50-0.80/ft2) and compaction equipment or contractor labor.