The Formula: Cubic Yards First, Then Tons
Gravel is ordered and priced by the ton, but you calculate by volume first. Start with cubic yards:
Length (ft) × Width (ft) × Depth (in) ÷ 324 = cubic yards
Then convert to tons by multiplying cubic yards by the material's density. Different materials have different weights per yard:
- Crusher run / #411: ~1.35 tons per cubic yard
- #57 washed stone: ~1.25 tons per cubic yard
- Pea gravel: ~1.3 tons per cubic yard
These are approximate — actual weight varies with moisture content and source quarry — but they're accurate enough for ordering. When in doubt, round up.
Build It in Two Layers
A gravel driveway that lasts is built in two layers. Installing only a surface layer on unprepared subgrade is the main reason gravel driveways fail within a few years — soft spots develop, ruts form, and the gravel sinks into the subsoil.
Base Layer: 4–6 inches of Crusher Run
Crusher run (also called #411) is a blend of crushed limestone and stone dust. Unlike washed stone, it contains the full gradation of particle sizes from 3/4 inch down to fines. Those fines fill the voids between larger pieces and lock everything together when compacted. The result is a dense, stable layer that holds the surface material above it and prevents the entire driveway from sinking over time.
Minimum base depth for passenger vehicles is 4 inches of compacted crusher run. For regular truck traffic or anything heavier, go 6 to 8 inches.
Surface Layer: 2–3 inches of Your Finish Material
The surface layer goes over the compacted base. Common options:
- Crusher run: The most economical option. Also the best performing — angular, self-locking, holds position under tire traffic. Works well for both base and surface.
- #57 stone: Clean, washed limestone. Drains well and looks uniform. Slightly less stable than crusher run because there are no fines to lock pieces in place — it will shift more under repeated turning.
- Pea gravel: Rounded, smooth. Decorative look but the worst choice for performance. It migrates under tires and requires edging on both sides to stay contained. Reserve it for low-traffic or decorative areas.
For a full comparison of surface material options, see best gravel for driveways in Missouri.
Reference Table: Common Driveway Sizes
Driveway Gravel Calculator — Two-Layer Build
Base layer = 6 inches crusher run (×1.35 tons/yd³). Surface layer = 3 inches #57 stone (×1.25 tons/yd³).
| Driveway | Length | Width | Base CY | Base Tons | Surface CY | Surface Tons | Total Tons |
|---|---|---|---|---|---|---|---|
| Small | 50 ft | 10 ft | 9.3 | 12.5 | 4.6 | 5.8 | 18.3 |
| Standard | 100 ft | 12 ft | 22.2 | 30.0 | 11.1 | 13.9 | 43.9 |
| Long | 200 ft | 12 ft | 44.4 | 60.0 | 22.2 | 27.8 | 87.8 |
| Wide | 100 ft | 16 ft | 29.6 | 40.0 | 14.8 | 18.5 | 58.5 |
Compaction Changes the Math
The depths in the table above are compacted depths — the target measurement after the material has been mechanically compacted. Crusher run compresses 20 to 25 percent under a plate compactor or roller. That means to achieve 6 inches of compacted base, you need to deliver roughly 7.5 to 8 inches of loose material before compaction.
Practical rule: add 20% to your base layer tonnage to account for compaction. The table above reflects pre-compaction ordering volumes.
Compaction must be done in lifts. Never dump all 6 inches at once and try to compact it in a single pass. The correct method is 3-inch lifts: spread 3 inches, compact fully, then spread the second 3-inch lift and compact again. Each lift must be compacted before the next goes on top. Skipping this step produces a driveway that looks solid at first and develops soft spots within one Missouri winter.
Don't skip the compaction step. A plate compactor rental runs $75–$100/day and is available at every equipment rental yard in Jefferson County. It's not optional — loose crusher run will never achieve the density of properly compacted material, regardless of how much traffic rolls over it.
Delivery Logistics in Jefferson County
J1S runs quad-axle dump trucks that carry 14 cubic yards per load. At crusher run density, that's approximately 18 to 19 tons per load. At #57 stone density, roughly 16 to 18 tons, depending on moisture.
For a small driveway calculating to under 15 tons, you'll still receive a full truck load — which usually isn't a problem since any leftover material can be used elsewhere on the property. For projects where a full 14-yard load is genuinely too much, contact us to discuss options before ordering.
Large driveways — the "Long" and "Wide" examples in the table — require multiple loads. A 200-foot driveway at two layers needs approximately 88 tons total, which is roughly 5 to 6 truck loads. Coordinate the delivery sequence: base loads first, compact between loads if you're doing it by hand, then surface loads.
Before scheduling, verify truck access: check for overhead obstructions along the drive path (tree branches, utility lines), confirm ground conditions are firm enough to support the loaded truck, and identify where the driver can turn around or back out.
Missouri Subgrade: The Clay Problem
Jefferson County's subsoil is primarily clay — the same expansive clay that causes foundation movement and heaves sidewalks. Clay subgrade is the enemy of gravel driveways. When it's wet, it's soft and unstable. When it's dry, it shrinks and shifts. Gravel placed directly on unprepared clay will eventually sink and rut, regardless of how much material you put down.
For a new driveway on raw clay, consider placing geotextile fabric before the base layer goes in. The fabric prevents the gravel from migrating down into soft clay during wet conditions — essentially acting as a separator layer. This adds a few hundred dollars to the project cost and adds years to the driveway's useful life.
Drainage crowning matters too. The center of the driveway surface should sit slightly higher (1 to 2 percent grade) than the edges so water sheets off to the sides rather than sitting in the middle and softening the base. Missouri's freeze-thaw cycle will find any water that pools on the surface and use it to break the driveway apart from below.
Long-Term Maintenance
A properly built gravel driveway requires periodic maintenance, not a full rebuild. Planning for this upfront is cheaper than emergency regrading after years of neglect.
- Surface replenishment: Add 1 to 2 inches of surface gravel every 2 to 3 years as the existing surface compacts and spreads at the edges. This is a partial load, not a full driveway project.
- Regrading: After significant rain events or winters, the surface develops ruts from repeated tire paths. Periodic dragging or box-blade grading restores the crown and fills the ruts. Many landowners do this with a tractor annually.
- Rebase: A full rebase — stripping the surface, regrading the subgrade, adding fresh base and surface material — is typically needed every 10 to 15 years on heavily used driveways. Less frequently on light-use rural drives.