Road Base Calculator

What the Road Base calculator computes

Road Base is a graded crushed-stone blend (fines through 1.5 inch fragments) designed to compact into a load-bearing base course under roads, driveways, parking lots, and structures. The calculator computes cubic yards and tons needed for a specified area at a specified compacted depth. Road Base density runs about 2,850 lb per cubic yard.

The calculator handles two common scenarios. For driveway and walkway base, the depth is 4 to 6 inches in two compacted lifts. For commercial road and parking lot base, the depth is 8 to 12 inches in two or three lifts. A 1,000 square foot driveway base at 6 inches compacted depth needs about 18 cubic yards or 26 tons.

Road Base composition and regional names

Road Base goes by different names in different US regions. Class 5 Base is the Upper Midwest term (Minnesota, Wisconsin, the Dakotas) for the same product. Crusher Run is the Southeast term. Quarry-Process or "QP" is used in parts of the Northeast. All refer to the same general product: a graded blend of stone dust through 1 to 1.5 inch crushed stone fragments.

The gradation is what makes Road Base compactable. The fine fraction (stone dust through 1/4 inch) fills the voids between larger fragments. When compacted by a vibratory roller or plate compactor, the mass interlocks into a near-concrete density. This compaction property is what distinguishes Road Base from a single-size aggregate like #57 Crushed Stone or Pea Gravel, which cannot achieve the same compacted density because there are no fines to fill voids.

The visual cue at the yard is the fines content. Road Base looks darker and dustier than single-size aggregates because of the fine fraction. A handful contains visible sand-sized particles mixed with stone fragments.

Compaction technique for Road Base

Compaction is the entire reason Road Base exists. Without compaction, Road Base is just unscreened gravel that performs no better than common Fill Dirt. Properly compacted Road Base achieves 95 to 100 percent of natural soil density and behaves like a paved slab under load.

The compaction sequence: place Road Base in lifts no thicker than 4 inches (uncompacted depth). Run a vibratory roller or plate compactor in overlapping passes across the lift. Repeat until the surface stops settling under additional passes. For commercial projects, lab-tested compaction (Proctor test) confirms density before the next lift is placed.

Moisture matters too. Road Base compacts best at 4 to 6 percent moisture content. Bone-dry base does not bind; saturated base squishes rather than locking. Mist the lift lightly with a garden hose before compaction if the material is dust-dry from a hot dry delivery day.

When Road Base is the right choice

Use Road Base for any application where compacted aggregate needs to support load. Residential driveway base under #57 Crushed Stone or Pea Gravel surface. Driveway entirely of Road Base where the dust binds the top surface into a paved-feeling drive. Parking lot base under asphalt or concrete paving. Shed pad foundation under a poured slab. Retaining wall base under the first block course.

Use Crusher Run instead of Road Base if your regional supplier uses the Crusher Run terminology; the products are interchangeable. Use Paver Base (finer, screened to 0 to 1/4 inch) instead of Road Base specifically for paver-stone installs where the bedding layer needs to be more uniform.

Do not use Road Base for drainage trenches, French drains, or anywhere water needs to flow through void space. The fines content that makes Road Base great for load support also clogs the void space that drainage applications need.

Pricing and project planning

Road Base delivers at $35 to $52 per ton across our service area. Full-truck orders of 16 tons or more save 15 to 20 percent off the per-ton rate. For a 1,000 square foot driveway base, expect 26 tons of Road Base at $1,000 to $1,400 delivered. Add the finish course (Crusher Run, #57 Crushed Stone, or asphalt paving) on top of the base for the complete driveway cost.

Same-day delivery windows are usually open before 11 AM with 1 to 2 business day lead times. Plan the delivery for a dry day; Road Base in heavy rain becomes harder to compact and the install timeline slips. Stage the drop on the existing driveway near the project area to minimize wheelbarrow distance during install.

Compactor rental for the install runs $60 to $120 per day for a plate compactor (residential scale) or $200 to $400 for a vibratory roller (commercial scale). Rent the equipment in advance; the post-delivery rush to find a compactor is the most common reason base courses get under-compacted.

Geotextile fabric on soft-soil sites

Road Base over poorly draining clay or organic soil settles and fails despite proper compaction because the base pumps fines from the underlying soil up into itself over time, losing strength gradually. Geotextile fabric between the native soil and the base course solves this problem by physically separating the two layers.

Two fabric types apply. Woven geotextile (the lower-cost, higher-strength option) handles separation and reinforcement. Non-woven geotextile (the higher-cost, more permeable option) handles separation and drainage. For most driveway and parking applications over normal soils, woven works at $0.30 to $0.60 per square foot. For wet sites or sites needing drainage flow through the fabric, non-woven runs $0.50 to $1.10 per square foot.

Install the fabric directly on the prepared subgrade before any base material goes down. Overlap adjacent fabric strips by 12 to 18 inches at seams. Pin the fabric to the soil with 6 inch landscape staples every 18 inches along edges and seams to keep it in place during base placement.

The fabric pays back its cost within 5 to 7 years on weak soil sites by extending base course life. On stable soils (well-drained sand or gravel subgrade), the fabric is overkill and adds cost without benefit. The decision rule: if water pools on the prepared subgrade after a heavy rain or your shovel sinks easily, use the fabric; if the subgrade drains within an hour, skip it.

Sites with high water tables also benefit from drainage stone above the fabric layer. A 4 to 6 inch layer of Drain Rock between the fabric and the main base course provides a capillary break and lets water that does reach the subgrade flow horizontally to the edges instead of pooling. This three-layer system (fabric, drain rock, road base) costs roughly 30 percent more than the basic two-layer install but doubles or triples expected life on chronically wet sites.