Calculate gravel volume, weight and cost for driveways, paths, drainage and landscaping — with verified densities by material.
Typical starting points: decorative gravel 0–5%, pea gravel 5–10%, crushed rock 10–15%, road base 15–20% — angular material with fines compacts more than rounded, uniform stone.
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| Item | Value |
|---|
Crushed rock and gravel are essential materials in Australian construction and landscaping. They are sold by weight (tonne) or volume (m³) depending on the supplier.
| Application | Material | Depth |
|---|---|---|
| Driveway (domestic) | Crushed rock / blue metal | 100mm compacted |
| Garden path | Pea gravel / river pebbles | 50–75mm |
| Drainage (around pipes) | Coarse gravel | Varies |
| Under slab | Crusher dust / compacted gravel | 75–100mm |
| Decorative garden | River pebbles / quartz | 50–75mm |
Written and reviewed by Mohsin Iqbal · Last reviewed August 2026
Gravel is loose rock fragments, either naturally rounded (river or pea gravel) or mechanically crushed (crushed rock, road base, blue metal). It's sold by weight (tonnes) even though you measure your project by volume (cubic metres) — the conversion between the two depends entirely on the material's density, which is why the same 3 m³ hole needs a different tonnage of pea gravel than it does of road base.
The process has three steps: find the area, multiply by depth to get volume, then convert volume to weight using the material's density.
Volume (m³) = Area (m²) × Depth (m)
Order volume = Volume × (1 + waste% ÷ 100) × (1 + compaction% ÷ 100)
Depth is almost always specified in millimetres even when the rest of your measurements are in metres or feet — a "100mm" driveway base is far easier to specify and check than "0.1m," which is why this calculator keeps depth in its own field regardless of which unit you're using for length and width.
Weight (kg) = Order volume (m³) × Density (kg/m³)
Tonnes = Weight (kg) ÷ 1,000
This is the step people most often get wrong — using one generic "gravel weighs about 1.5 tonnes per m³" figure for every material, when road base and pea gravel can differ by 15–20% in density for the exact same volume.
| Material | Typical density | Coverage per tonne (100mm depth) |
|---|---|---|
| Pea gravel / river rock | 1,500 kg/m³ | ~6.7 m² |
| Crushed rock / blue metal / crushed stone / granite / sand | 1,600 kg/m³ | ~6.3 m² |
| Limestone | 1,450 kg/m³ | ~6.9 m² |
| Road base / crusher dust | 1,700 kg/m³ | ~5.9 m² |
These are commonly cited planning densities, cross-checked against multiple independent construction and landscaping references — actual density varies by supplier, moisture content and particle size, so use the custom density option if your supplier provides a specific figure.
| Type | Description | Common use |
|---|---|---|
| Crushed rock / blue metal | Angular, mechanically crushed | Driveways, general fill |
| Road base | Graded crushed rock that compacts densely | Driveway and road sub-base |
| Pea gravel | Small, naturally rounded stones | Paths, decorative ground cover |
| River rock | Larger, naturally rounded stones | Decorative landscaping, drainage |
| Crusher dust | Fine crushed rock, almost sand-like | Paver bedding, compaction layers |
| Decorative gravel | Coloured or textured stone | Garden beds, feature areas |
Residential driveways typically use 100–150mm of compacted road base, sometimes with a decorative surface layer on top. Deeper is better for driveways carrying heavier vehicles.
Decorative gravel for garden beds is usually laid at 50–75mm — enough to suppress weeds and look intentional without excessive cost.
Paths generally use 50–75mm of pea gravel or similar, sometimes over a compacted road base layer if the path needs to bear regular foot traffic in wet conditions.
Drainage trenches and French drains typically need 200–300mm of clean, angular gravel with minimal fines, since fine material clogs drainage capacity over time.
Road base is a graded mix designed to compact into a dense, stable sub-base — it's denser than decorative gravel (typically ~1,700 kg/m³) precisely because the mix of particle sizes fills the gaps between larger stones.
Loose gravel settles and compacts once laid and rolled or trafficked. How much depends heavily on the material — angular, fines-rich material like road base locks together and compacts far more than rounded, uniform stone like pea gravel, which tends to roll rather than settle. This calculator's compaction allowance adds extra material up front to account for that settling, separately from the waste allowance, which covers spillage and spreading losses instead. The two are genuinely different things and shouldn't be confused: waste is material you lose, compaction is volume the material itself loses once it beds in.
| Material | Typical compaction |
|---|---|
| Decorative gravel | 0–5% |
| Pea gravel | 5–10% |
| Crushed rock | 10–15% |
| Road base | 15–20% |
These are starting points, not guarantees — actual compaction depends on moisture, layer thickness and how thoroughly it's rolled or tamped. For a deep base layer, compact in stages (roughly 50–100mm at a time) rather than one thick pour, since only the top portion of a thick loose layer actually compacts when rolled.
Wet gravel weighs more than dry gravel — commonly around 10–15% more, since water fills the void space between particles. If your supplier weighs a load after rain or from a wet stockpile, the tonnage you receive for a given volume can come in on the heavier side of what this calculator estimates. This calculator, like most gravel calculators, works from dry-material densities — treat the weight figures here as a planning estimate, and expect some natural variation depending on recent weather and how the material has been stored.
10% is a reasonable default for a straightforward rectangular area. Irregular shapes, sites with obstacles, or hand-spreading over a large area can reasonably warrant more.
Total cost combines material cost (tonnes × price per tonne) and delivery, which suppliers usually charge separately and which can vary significantly by distance from the quarry or yard.
Australian suppliers sell gravel and crushed rock by the tonne, delivered by tipper truck, with common materials including blue metal, road base and decorative gravels like river pebble. Bulk bags and trailer-load quantities are common for smaller residential jobs.
US suppliers commonly quote by the cubic yard or by the ton (a US short ton is 907kg, about 10% lighter than a metric tonne — worth checking which one your supplier means for a large order). Pea gravel and crushed stone are the most common landscaping materials.
UK suppliers commonly sell "MOT Type 1" for driveway and road sub-base, a densely graded crushed stone that compacts to around 1,850–1,950 kg/m³ because its mix of fine and coarse particles fills the voids between larger stones — noticeably denser than standard decorative gravel.
| Step | Working | Result |
|---|---|---|
| Area | 12m × 3m | 36.00 m² |
| Volume | 36.00 × 0.1m | 3.600 m³ |
| With 10% waste | 3.600 × 1.10 | 3.960 m³ |
| Weight (road base, 1,700 kg/m³) | 3.960 × 1,700 | 6.732 tonnes |
Area 8.00 m², volume 0.440 m³ with 10% waste, weight 0.66 tonnes at pea gravel's 1,500 kg/m³ density.
Area 2.40 m², volume 0.660 m³ with 10% waste, weight 0.99 tonnes.
Area 45.00 m², volume 7.425 m³ with 10% waste, weight 12.62 tonnes — more than two standard 6-tonne truck loads.
A 12m × 3m driveway and an 8m × 1m path together: combined area 44.00 m², volume 4.840 m³ with 10% waste, weight 7.74 tonnes at 1,600 kg/m³.
Multiply your area (length × width, in m²) by depth (in metres) to get volume, add a waste allowance, then multiply by your material's density to get weight in tonnes. A 12m × 3m driveway at 100mm depth in road base needs about 6.73 tonnes.
Take your order volume in cubic metres and multiply by the material's density in kg/m³, then divide by 1,000. For a 3.96 m³ order of road base (1,700 kg/m³), that's 6.73 tonnes.
Area × depth gives volume; volume × density gives weight. This calculator does both automatically once you enter your shape, depth and material.
It depends on the material — pea gravel and river rock are around 1,500 kg/m³, crushed rock and granite around 1,600 kg/m³, and road base or crusher dust around 1,700 kg/m³. A generic "1.5 tonnes per m³" figure can be meaningfully wrong for denser materials.
Divide your total weight in kilograms by the bag size (commonly 20kg, 25kg or 40kg). For most driveway or large landscaping jobs, bulk (tonne) delivery works out far cheaper than bagged material — this calculator flags that when the bag count gets very high.
It depends on depth and material — at 100mm depth, 1 m² needs 0.1 m³ of gravel, which is roughly 0.16-0.17 tonnes depending on density. Shallower depths need proportionally less.
100-150mm of compacted road base is typical for a residential driveway. Driveways carrying heavier vehicles benefit from the deeper end of that range.
Use the figure for your specific material from the dropdown, or enter a custom density if your supplier provides one — supplier-specific figures are more accurate than general planning densities for a large or expensive order.
Small, naturally rounded stones, typically 10-20mm, commonly used for garden paths and decorative ground cover. Its rounded shape makes it comfortable to walk on but less stable underfoot than angular crushed rock.
Very fine crushed rock, almost sand-like in texture, commonly used as a compaction layer under pavers or as a binding layer in road base mixes. Its fine particles pack tightly, giving it a higher density than coarser gravel.
Delivery cost varies by distance from the supplier's yard or quarry and isn't something a general calculator can estimate accurately — get a quote from your specific supplier, and enter it into the delivery cost field to include it in your total.
Depends on the truck size — a small rigid truck typically carries 5-6 tonnes, so divide your total tonnage by the truck's capacity and round up. This calculator shows an estimate based on a standard 6-tonne truck.
10% is a reasonable default for a straightforward rectangular area. Irregular shapes, obstacles, or hand-spreading over a large area can reasonably warrant more.
Yes — select your shape, a shallow depth (50-75mm is typical for decorative gravel), and a landscaping material like pea gravel or decorative gravel from the material list.
Yes — select Road Base from the material list, which uses a higher density (1,700 kg/m³) reflecting how densely it compacts compared to decorative gravel.
Waste covers material you lose during spreading and handling. Compaction covers volume the material itself loses once it settles and beds in under rolling or traffic — they're separate effects and both matter for an accurate order on a compacted base layer.
Because density varies by material — a denser material like road base packs more mass into the same volume than a looser material like pea gravel, so the same 100mm depth over the same area needs more tonnes of the denser material.
| Gravel Type | Bulk Density | Common Use |
|---|---|---|
| Pea gravel / river pebbles | ~1.5-1.6 t/m³ | Garden beds, decorative |
| Crushed rock (20mm) | ~1.8-1.9 t/m³ | Driveways, drainage |
| Blue metal (20mm) | ~1.9-2.0 t/m³ | Concrete aggregate, driveways |
| Decomposed granite | ~1.6-1.8 t/m³ | Paths, driveways |
| Road base (compacted) | ~2.0-2.2 t/m³ | Sub-base for driveways |
| Application | Recommended Depth |
|---|---|
| Decorative garden bed | 40-50 mm |
| Landscaping path | 50-75 mm |
| Residential driveway | 75-100 mm over compacted base |
| Drainage layer | 100-150 mm |
How many tonnes of gravel do I need?
Calculate volume in m³ (length × width × depth in metres), then multiply by the bulk density. For pea gravel: 1.5-1.6 t/m³. For crushed rock/blue metal: 1.8-2.0 t/m³. Add 10-15% for compaction and settling. Most bulk suppliers sell by the tonne — get quotes from local landscape suppliers as delivery costs significantly affect total price.
How deep should gravel be for a driveway in Australia?
Standard recommendation for a residential gravel driveway: 75-100mm of compacted crushed rock or road base over a 100mm compacted sub-base, with optional decorative gravel on top. Total depth: 200-250mm. For vehicle traffic on sandy or unstable soils, deeper bases (300mm+) may be required. Geotextile fabric beneath the gravel layer prevents mixing with soil.
How much area does 1 tonne of gravel cover?
At 50mm depth: 1 tonne of pea gravel (1.5 t/m³) covers approximately 1/1.5 × (1/0.05) = 13.3 m². At 75mm: approximately 8.9 m². At 100mm: approximately 6.7 m². These are theoretical figures — actual coverage varies by compaction and gravel type. Always round up when ordering.
How do I figure out how much gravel I need?
To work out gravel, multiply the area (length × width) by the depth to get the volume, then convert to weight using gravel density (about 1.5 tonnes per cubic metre). This gravel calculator does the figuring for you — enter your dimensions and depth.