Road Base Calculator
Calculate exactly how much road base, DGB20, or crusher dust you need for your driveway, paving base, or construction project. Get results in cubic metres, tonnes, and bags.
Calculate Your Road Base
Recommended depth: 100-200mm for driveways and paths
Total Volume
Volume: Length × Width × Depth (converted to metres). For circles: π × radius² × depth. For triangles: ½ × base × height × depth.
Weight: Volume × road base density. DGB20 has a density of 1.8 t/m³, while crusher dust is lighter at 1.6 t/m³.
Bags: Weight in tonnes × 50 (standard 20kg bags). We round up to ensure you have enough material.
Bulka Bags: Volume ÷ 1.0 (standard 1m³ bulka bag). Rounded up for ordering purposes.
How to Calculate Road Base for Your Project
Calculating the correct amount of road base is essential for any driveway, pathway, or construction project in Australia. Road base provides the crucial structural layer that supports traffic loads and ensures long-lasting surfaces. Our calculator helps you determine exactly how much you need.
Understanding Road Base Measurements
In Australia, road base is sold by the tonne or cubic metre. Since road base is dense and heavy (up to 1.8 tonnes per cubic metre), most suppliers price by weight. Our calculator provides both measurements, making it easy to get accurate quotes and order the right amount.
Choosing the Right Road Base Depth
For pedestrian paths and light-use areas where vehicles won't travel, 100mm of compacted road base provides sufficient support. Standard residential driveways and parking areas perform best with 150mm of properly compacted material—this depth handles regular car traffic without issues. If you're expecting heavy vehicles like delivery trucks or caravans, or if your subgrade soil is soft clay or poorly draining, increase to 200mm or more to prevent rutting and failure over time.
Types of Road Base Available in Australia
DGB20 at 1.8 tonnes per cubic metre is Australia's most widely used road base, containing a carefully graded mix of particles from fine dust up to 20mm stones. This grading is what gives it structural strength—the different particle sizes lock together during compaction to create a solid foundation for driveways, paths, and building slabs. DGB10 at the same density offers finer grading with maximum particles of 10mm, making it better suited for thinner applications or where you need tighter compaction under pavers.
FCR (Fine Crushed Rock) at 1.7 t/m³ contains even smaller particles than DGB10 and is commonly used as a finishing layer or directly under pavers where a smoother surface is required. For environmentally conscious projects, recycled road base at 1.6 t/m³ is manufactured from crushed concrete and brick, offering good performance for non-structural applications at a lower cost. Quarry rubble at 1.8 t/m³ is unprocessed material straight from the quarry, suitable for bulk filling and rural driveways where precise grading isn't critical. Crusher dust at 1.6 t/m³ is the fine material produced during crushing operations—useful as a surface layer or paver bedding but not suitable as a structural base layer on its own.
Proper Road Base Installation
Successful road base installation requires attention to technique at every stage. Begin by excavating to the correct depth, remembering to account for both your base layer thickness and whatever surface material will go on top. Before adding any road base, compact your existing subgrade soil thoroughly—a weak foundation will cause problems regardless of how well you install the layers above.
When spreading road base, work in layers no thicker than 75mm and compact each layer fully before adding the next. Each layer should reach 95% or greater compaction density, which typically requires a vibrating plate compactor for paths and a roller for larger areas. Adding a light spray of water during compaction helps particles bind together and achieve maximum density. Finally, ensure you create a 1-2% cross-fall so water drains away from buildings and doesn't pool on the surface.
Road Base vs Gravel
Despite their similar appearance, road base and gravel serve fundamentally different purposes. Road base is engineered with a specific particle size distribution—called grading—that allows particles to lock together during compaction, creating a solid structural layer capable of supporting heavy loads. Gravel, by contrast, typically consists of single-sized decorative stones that don't compact or interlock. For proper driveway construction, always use road base as your structural foundation, then apply gravel, concrete, or asphalt as the finished surface.
Frequently Asked Questions
Calculate road base by measuring length × width × depth. For a 10m × 3m driveway at 150mm depth: 10 × 3 × 0.15 = 4.5 cubic metres. At 1.8 t/m³ density, that's approximately 8.1 tonnes of DGB20 road base.
In Australia, residential driveways typically need 100-150mm of compacted road base. For heavy vehicles or soft subgrade, increase to 200mm. Compact in 75mm layers, with each layer reaching 95%+ compaction before adding the next.
DGB20 contains particles up to 20mm and is the standard road base for driveways and paths. DGB10 has smaller particles (up to 10mm) and compacts more tightly, making it ideal for under pavers and finer finishes. Both have a density of approximately 1.8 t/m³.
Road base weighs approximately 1.6-1.8 tonnes per cubic metre depending on the type. DGB20 and DGB10 are typically 1.8 t/m³, while crusher dust is lighter at 1.6 t/m³. Our calculator provides automatic weight conversions for all types.
Crusher dust (fine crushed rock) is best as a surface layer or under pavers, not as structural road base. It lacks the larger aggregate that gives road base its load-bearing capacity. For driveways, use proper graded road base (DGB20) for the base layer.