Gravel Calculator
Gravel & Aggregate Calculator
Estimate aggregate for base layers, driveways, paths, and landscaping beds. Enter area and compacted thickness, apply a compaction factor and waste allowance to get your order volume — then optionally convert to tonnes using bulk density.
Gravel & Aggregate Calculator
Estimate order volume and weight with waste and compaction
Results
Enter dimensions above to calculate
How the Calculation Works
You order loose aggregate that will compact down to the finished depth. The diagram shows the three key depths and how they relate.
Step-by-Step Formulas
1. Calculate Area
Start with the footprint of the area to fill. Use length × width for rectangular pads, driveways, and paths — or diameter for circular pads and round features.
2. Compacted Volume
Thickness is the finished (compacted) depth of the base or fill layer. In metric enter centimetres; in imperial enter inches.
3. Compaction Factor
Because aggregate compacts under traffic and equipment, you must order more loose material than the finished compacted volume. A factor of 1.10 means order 10% extra to achieve the desired compacted depth.
4. Waste Allowance
Add waste for grading, spillage, uneven subgrade, and small measurement errors. 10% is a common starting point for simple rectangular areas.
5. Estimate Weight
Many suppliers price aggregate by the ton/tonne. Bulk density varies by material type, gradation, and moisture. Enter a supplier-specific value or use the material presets.
Typical Bulk Densities by Material
| Material | Metric | Imperial |
|---|---|---|
| Pea gravel | 1,500–1,600 kg/m³ | 94–100 lb/ft³ |
| Crushed stone (¾ in / 20 mm) | 1,600–1,700 kg/m³ | 100–106 lb/ft³ |
| Crushed stone (base aggregate) | 1,650–1,750 kg/m³ | 103–109 lb/ft³ |
| Sand (dry) | 1,450–1,600 kg/m³ | 91–100 lb/ft³ |
| Sand (wet) | 1,700–2,000 kg/m³ | 106–125 lb/ft³ |
| River gravel (rounded) | 1,550–1,650 kg/m³ | 97–103 lb/ft³ |
* Values are dry bulk densities and are indicative. Confirm with your supplier for accurate weight pricing.
Worked Example
Gravel base for a 10 m × 3 m pad, 10 cm compacted thickness, compaction factor 1.10, 10% waste, density 1,600 kg/m³.
💡 Pro tip
Place and compact gravel in lifts of 10–15 cm maximum. Compacting a thicker single layer often leaves a soft zone in the middle that causes settling over time. Use a plate compactor for granular base — vibration is the key, not just weight.
Frequently Asked Questions
- Should I order gravel by volume or by weight?
- Both are common. Landscapers often order by cubic yards/metres, while many suppliers sell by the ton/tonne. Weight depends on the bulk density and moisture of the material.
- What compaction factor should I use for gravel base?
- A compaction factor of 1.10 is a common rule of thumb for granular base. Actual compaction varies by material, moisture, and equipment — confirm with your supplier if precision matters.
- How much waste should I add?
- For simple rectangular areas, 5–10% is often enough. For irregular shapes, slopes, or rough subgrade, 10–15% may be more realistic.
- How deep should a gravel driveway base be?
- A gravel driveway for passenger vehicles is typically 10–15 cm (4–6 in) of compacted granular base. In freeze-thaw climates or soft soils, 20 cm (8 in) or more is common.