Gravel Calculator
Calculate exactly how much gravel, blue metal, or decorative pebbles you need for your driveway, pathway, or garden project. Get results in cubic metres, tonnes, and bags.
Calculate Your Gravel
Recommended depth: 50-100mm for pathways and driveways
Total Volume
Volume: Length × Width × Depth (converted to metres). For circles: π × radius² × depth. For triangles: ½ × base × height × depth.
Weight: Volume × gravel density. Blue metal has a density of 1.5 t/m³, while river pebbles are heavier at 1.6 t/m³.
Bags: Weight in tonnes × 50 (standard 20kg bags). We round up to ensure you have enough gravel.
Bulka Bags: Volume ÷ 1.0 (standard 1m³ bulka bag). Rounded up for ordering purposes.
How to Calculate Gravel for Your Project
Calculating the right amount of gravel for your Australian property is essential whether you're creating a driveway, pathway, drainage solution, or decorative garden feature. Our gravel calculator provides instant, accurate measurements to help you order the exact amount needed.
Understanding Gravel Measurements
In Australia, gravel is typically sold by the tonne or cubic metre. Since gravel is dense and heavy, weight-based pricing is common. Our calculator provides both volume and weight measurements, allowing you to compare quotes from different suppliers accurately.
Choosing the Right Gravel Depth
For decorative garden beds where gravel serves as a mulch alternative or for paths with only light foot traffic, 50mm provides adequate coverage while keeping costs reasonable. General pathways and residential driveways perform best with 75mm of gravel laid over a properly compacted roadbase foundation—this depth gives vehicles enough material to grip while remaining stable underfoot. In heavy traffic areas or where drainage is the primary concern, increase the depth to 100mm to ensure longevity and proper water flow.
Types of Gravel Available in Australia
Blue metal (also called bluestone) at 1.5 tonnes per cubic metre remains Australia's most popular choice for driveways and drainage applications. This crushed basalt ranges from dark grey to blue-black in colour, and its angular shape locks together during compaction to create an exceptionally stable surface. Crushed granite at 1.4 t/m³ offers similar performance with a broader colour palette ranging from gold to pink, making it popular for decorative paths where appearance matters as much as function.
River pebbles at 1.6 t/m³ are the heaviest option and feature smooth, rounded stones in natural earth tones. Their polished appearance makes them perfect for garden beds, water features, and areas where a softer aesthetic is desired—though their rounded shape means they don't compact as firmly as angular alternatives. Crushed sandstone at 1.4 t/m³ brings warm yellow to brown tones that complement heritage properties and native gardens beautifully, while crushed limestone at 1.5 t/m³ offers bright white to cream colours for a striking contrast in the landscape.
For environmentally conscious projects, recycled aggregate at 1.4 t/m³ is made from crushed concrete and brick, providing a sustainable option for non-decorative applications like drainage or base layers. Decorative pebbles at 1.5 t/m³ come in various colours and sizes for feature areas where visual impact is the priority.
Tips for Using Gravel
To ensure your gravel stays where you want it and performs well over time, always install landscape fabric underneath to prevent weeds from pushing through. Edge your gravel areas with steel, timber, or concrete borders to stop stones from migrating into surrounding lawn or garden beds. For driveways and high-traffic paths, compact your gravel in layers rather than all at once—this creates a much more stable surface that won't rut under vehicle tyres. One of gravel's key benefits is its permeability, allowing rainwater to drain through rather than running off, which makes it an excellent choice for areas where you want to reduce stormwater issues. For any driveway application, always install gravel over a properly compacted roadbase layer—the gravel alone won't provide the structural support vehicles require.
Gravel vs Roadbase
While both are crushed stone, gravel and roadbase serve different purposes. Gravel is typically single-sized decorative stone for surface applications, while roadbase contains a graded mix of particle sizes specifically engineered to compact into a solid structural layer. For proper driveway construction, you need both—roadbase underneath to provide strength and stability, with gravel on top for the finished surface.
Frequently Asked Questions
Calculate driveway gravel by measuring length × width × depth (in metres). For a 10m × 3m driveway at 75mm depth: 10 × 3 × 0.075 = 2.25 cubic metres. Use our calculator to get instant results including weight conversions for ordering.
For residential driveways in Australia, gravel should be 75-100mm deep over a compacted roadbase layer. For light traffic paths, 50mm is sufficient. Always compact gravel in layers of no more than 75mm for best results.
Blue metal (1.5 t/m³) is crushed basalt/bluestone, dark grey in colour, commonly used for driveways and drainage. Crushed granite (1.4 t/m³) is lighter in colour with gold/brown tones, popular for decorative paths and garden features.
Gravel typically weighs 1.4-1.6 tonnes per cubic metre depending on the type. Blue metal is approximately 1.5 t/m³, river pebbles are 1.6 t/m³, and crushed granite is 1.4 t/m³. Our calculator provides automatic weight conversions.
While decorative pebbles look attractive, they're not ideal for driveways as they can scatter and don't compact well. For driveways, use angular crushed rock like blue metal or granite that locks together. Save decorative pebbles for garden beds and paths.