Road Base Calculator (Compacted Sub-Base)
Estimate tonnage for compacted aggregate sub-base under asphalt, concrete, or gravel surfaces — road-building grade with the higher density typical for dense-graded aggregate.
Road Base Calculator
Enter project dimensions below — results update instantly. Switch units freely.
Estimates assume typical industry density and waste factors. Always verify with your supplier and local building code before purchasing material.
Road Base vs. Gravel: Same Word, Different Grade
‘Road base’ and ‘gravel’ get used interchangeably in casual conversation. On a job site they mean different products:
- Gravel — generic term for any loose stone aggregate, rounded or angular
- Road base — specific dense-graded aggregate engineered for compaction under pavement
Road base has three distinguishing features:
- Dense gradation — full size range from dust to 1 inch. Small particles fill voids between large ones for maximum density.
- Angular shape — crushed stone, not river rock. Angular faces interlock when compacted.
- Plasticity index controlled — moderate clay content allows compaction to 95%+ Proctor without being susceptible to frost heave.
Other names for the same material: DGA (Dense-Graded Aggregate), crusher run, Class 5 (Midwest), 3/4 minus, Base Type 1. All referring to compactable sub-base aggregate at ~110 lb/ft³.
Road Base Thickness by Application
Road base density at 110 lb/ft³ is ~10% higher than uniformly graded #57 because of the full gradation filling voids.
Road base thickness by pavement type:
- Residential walkway: 4 in minimum
- Residential driveway (passenger cars): 4-6 in
- Driveway with occasional trucks / RV: 8 in
- Commercial parking lot: 8-10 in
- Heavy commercial / truck staging: 12 in
- Local road: 8-12 in
- State highway: 10-14 in
- Interstate: 12-18 in
Compaction in lifts of 6-8 inches max. Deeper lifts don't reach specified density at the bottom. A plate compactor handles up to 6 in; a vibratory roller handles up to 8-10 in per lift.
| Area | 4 in depth | 6 in depth | 8 in depth | 12 in depth |
|---|---|---|---|---|
| 100 ft² | 1.8 tons | 2.75 tons | 3.67 tons | 5.5 tons |
| 500 ft² | 9.2 tons | 13.8 tons | 18.3 tons | 27.5 tons |
| 1,000 ft² | 18.3 tons | 27.5 tons | 36.7 tons | 55 tons |
| 2,500 ft² | 45.8 tons | 68.8 tons | 91.7 tons | 137.5 tons |
| 5,000 ft² | 91.7 tons | 137.5 tons | 183.3 tons | 275 tons |
| 10,000 ft² | 183 tons | 275 tons | 367 tons | 550 tons |
Based on 110 lb/ft³ compacted density. Order 10% extra for compaction loss; in-place volume is smaller than ordered volume.
| Sieve Size | % Passing (typical) |
|---|---|
| 1 in (25 mm) | 100% |
| 3/4 in (19 mm) | 85-100% |
| 3/8 in (9.5 mm) | 50-85% |
| #4 (4.75 mm) | 35-65% |
| #40 (0.425 mm) | 15-30% |
| #200 (0.075 mm) | 5-15% |
AASHTO M147 & state DOT specs vary slightly. Full gradation from 3/4 in down to fines enables maximum compaction density.
Real-World Example Calculations
Country Driveway 12 × 200 ft @ 6 in base
New gravel driveway sub-base from road to barn.
- Length × Width
- 200 × 12 ft
- Depth
- 6 in
- $/ton
- $22
Takeaway: 3 tri-axle deliveries. Place in 2 × 3-in lifts, compact each. Top with 2 in #57 stone for driving surface.
Parking Lot Sub-Base 100 × 80 ft @ 8 in
Commercial parking lot base under 3-in asphalt surface.
- Length × Width
- 100 × 80 ft
- Depth
- 8 in
- $/ton
- $24
Takeaway: ~13 tri-axle deliveries. Place in 4-in lifts; compact with vibratory roller to 95% Proctor before asphalt placement.
Highway Sub-Base 0.25 mi × 48 ft @ 12 in
State highway rebuild with full-depth sub-base replacement.
- Length × Width
- 1,320 × 48 ft
- Depth
- 12 in
- $/ton
- $20
Takeaway: Multi-week project. Place in 6-in lifts, compact each with sheepsfoot or vibratory roller. Density testing every 200 ft.
Frequently Asked Questions
How much road base do I need for a driveway?
For a standard 600 ft² driveway at 6 inches compacted: ~16.5 tons of road base. At 4 inches: 11 tons. At 8 inches: 22 tons. Add 10% for compaction loss.
How thick should road base be?
Residential driveway: 4-6 inches compacted. Light commercial: 6-8 inches. Heavy commercial: 8-12 inches. Local road: 8-12 inches. Thinner than 4 inches and the base can't support vehicle loads, causing pavement failure from below.
What's the difference between road base and crusher run?
Essentially the same material. Road base is a function name; crusher run (or DGA, dense-graded aggregate) is a specific product code. Crusher run = full gradation from dust to 3/4 inch, which is the standard road base spec in most US regions.
How do I compact road base?
In lifts of 6-8 inches maximum. Small areas: plate compactor ($60/day rental). Large areas: vibratory roller ($350-500/day). For highway work: sheepsfoot or smooth-drum vibratory roller. Moisture helps compaction — slightly damp base compacts better than bone-dry.
Is road base the same as gravel?
No. Road base (crusher run, DGA) has a full gradation from fines to 3/4 inch that compacts dense. Gravel is typically uniformly graded (all stones similar size) with open voids that don't compact. For a structural sub-base, always spec road base.
How much does road base cost per ton?
In 2026: $18-28 per ton at the quarry. Delivered to residential sites: $40-55 per ton. Road base is one of the cheapest aggregates by design — it's mass-produced at every quarry.
Can I put road base over existing dirt?
Yes — but first remove any organic material (grass, roots, topsoil) and compact the subgrade. Over soft clay, add a geotextile fabric between the subgrade and road base to prevent the two layers from mixing. Geotextile adds $0.30-0.60 per ft² and prevents the ‘pumping’ failure where clay migrates up into the stone.