🪨 Road Base Calculator — Estimate Sub-base Thickness, Tonnage & Cost

Q: How much does road base cost per ton?

Road base costs $12-$40 per ton depending on material type and location. Crusher run is $12-$25/ton, crushed stone is $15-$30/ton, limestone base is $18-$35/ton, and pre-mixed road base blend is $20-$40/ton. Delivery adds $50-$150 depending on distance and quantity.

Q: How many tons of road base per square foot?

At 6 inches depth with crusher run (105 lbs/ft³), you need approximately 0.029 tons per square foot including 10% waste. A 600 sq ft driveway at 6 inches deep needs roughly 17.5 tons of road base material.

Q: Can I pave asphalt over existing gravel?

Yes, you can pave asphalt over existing gravel if the base is solid and well-compacted. Add 2-4 inches of fresh base material on soft spots, compact thoroughly, apply a tack coat, then pave. The existing gravel must be at least 4 inches thick and free of organic material.

Q: What is the difference between sub-base and base course?

Sub-base is the lower, coarser layer placed directly on the prepared subgrade (native soil). Base course is the upper, finer layer placed on top of the sub-base. For residential driveways, a single 4-6 inch layer of crusher run typically serves as both sub-base and base course.

Use this free road base calculator to estimate how much crushed stone, aggregate, or sub-base material you need for driveways, parking lots, and roads. All results include a 10% overage for compaction loss and waste. For asphalt material quantities, try our asphalt calculator.

Why Road Base Matters Before Paving

The road base — also called the sub-base or aggregate base course — is the foundation that supports asphalt, concrete, or any other surface material. Without a properly compacted base, even the highest-quality asphalt will develop cracks, potholes, and structural failures within 2-3 years.

Road base serves three critical functions: load distribution (spreading vehicle weight across a wider area), drainage (angular crushed stone allows water to flow away from the surface), and frost protection (preventing freeze-thaw cycles from heaving pavement). Getting the base right is the single most important step in any paving project.

Whether you're building a residential driveway, commercial parking lot, or rural road, use our road base calculator above to estimate the exact tonnage of aggregate material you'll need. The calculator automatically includes a 10% overage to account for compaction and waste.

Road Base Thickness Guide by Project Type

The required depth of road base depends on the expected traffic load, soil conditions, and climate. Use this table as a starting point:

Application	Recommended Depth	Material	Notes
Residential driveway (cars)	4–6 inches	Crusher run	Minimum for a stable base
Residential driveway (heavy vehicles/RV)	6–8 inches	Crushed stone	Trucks, RVs, trailers
Commercial driveway	8–10 inches	Crushed stone	Mix of vehicle types
Parking lot (standard)	6–8 inches	Gravel	Cars and light trucks
Parking lot (heavy traffic)	10–12 inches	Crushed stone	Delivery trucks, buses
Private road	8–12 inches	Flex base	Depends on soil and traffic
Highway / arterial	12–18 inches	Engineered base	Engineered spec required

Road Base Material Types & 2026 Costs

Choosing the right material for your road base affects both cost and long-term performance. Here's a comparison of common base materials with current 2026 pricing:

Material	Cost/Ton (2026)	Density (lbs/ft³)	Best Use
Crushed Stone / Gravel	$15–$30	100	All-purpose base, good drainage
Crusher Run	$12–$25	105	Compacts best, most popular for driveways
Limestone Base	$18–$35	95	Strong, excellent drainage
Caliche / Flex Base	$8–$20	110	Southwest US, rural roads
Road Base Blend	$20–$40	115	Pre-mixed engineered base

The Road Base Formula

Our calculator uses the following industry-standard formulas to estimate road base material:

Volume (ft³) = Length × Width × (Depth ÷ 12)

Tonnage = Volume × Density ÷ 2,000

Total Tonnage = Tonnage × 1.10 (10% overage for compaction & waste)

Total Cost = Total Tonnage × Cost Per Ton

Worked Example

A 20 ft × 50 ft driveway with 6-inch crusher run at 105 lbs/ft³ and $25/ton:

Volume: 20 × 50 × (6 ÷ 12) = 500 ft³
Raw tonnage: 500 × 105 ÷ 2,000 = 26.25 tons
With 10% overage: 26.25 × 1.10 = 28.88 tons
Total cost: 28.88 × $25 = $721.88

Road Base vs. Gravel — What's the Difference?

Road base (also called "aggregate base course" or ABC) is made from angular, crushed stone with a mix of particle sizes including fine dust. The angular edges interlock when compacted, creating an extremely stable surface. This is what professionals use under asphalt, concrete, and pavers.

Gravel, by contrast, is often rounded and smooth — especially natural river gravel. Round stones don't interlock, making them poor choices for structural base layers. If you're installing a sub-base for paving, always use angular crushed material, not rounded gravel. For material quantities, use our gravel calculator for landscape gravel projects, and this road base calculator for structural base layers.

Frequently Asked Questions

How deep should road base be for a driveway?

For a residential driveway with cars only, 4–6 inches of compacted road base is the standard recommendation. For driveways that will handle heavier vehicles like RVs, trucks, or trailers, increase the depth to 6–8 inches. Commercial driveways need 8–10 inches. Always compact the base to at least 95% Proctor density — a plate compactor rental costs $50–100/day and makes a huge difference in long-term performance.

How much does road base cost per ton?

Road base material costs $12–$40 per ton in 2026, depending on the type and your location. Crusher run (the most popular choice) runs $12–$25/ton. Crushed stone is $15–$30/ton. Limestone base is $18–$35/ton. Delivery typically adds $50–$150 depending on distance and quantity. Most suppliers offer better per-ton pricing for full truckloads (10–14 tons).

How many tons of road base per square foot?

At 6 inches depth using crusher run (105 lbs/ft³), you need approximately 0.029 tons per square foot, including the 10% overage for compaction and waste. For quick estimates: a 600 sq ft driveway at 6 inches deep needs roughly 17.5 tons. A 1,000 sq ft area at 6 inches needs about 29 tons. Use the calculator above for precise quantities based on your specific material and depth.

Can I pave asphalt over existing gravel?

Yes, asphalt can be paved over existing gravel if the base is solid and well-compacted. Inspect the gravel for soft spots — add 2–4 inches of fresh crusher run on any areas that feel spongy. Compact the entire base thoroughly, apply a tack coat for adhesion, then pave. The existing gravel should be at least 4 inches thick and free of organic material, mud, or standing water.

What compaction rate is needed for road base?

Road base should be compacted to 95% Proctor density for optimal structural support. During compaction, the material compresses approximately 20–25% from its loose (dumped) state. This is why our calculator includes a 10% overage in all estimates. Use a vibratory plate compactor for thin lifts (2–3 inches at a time) and a roller for larger areas. Water the base lightly before compacting for best results.

What is the difference between sub-base and base course?

The sub-base is the lower, coarser layer placed directly on the prepared subgrade (native soil). It typically uses larger stone (1.5–2 inch) for drainage and load distribution. The base course is the upper, finer layer placed on top of the sub-base, usually 3/4-inch crusher run that compacts to a smooth surface. For residential driveways, a single 4–6 inch layer of crusher run typically serves as both sub-base and base course, simplifying the process.