How Much Aggregate Do I Need?

How We Calculated This

Aggregate quantity is calculated by multiplying the area by the depth to get a volume, then converting to weight using bulk density:

• Area: 10m²
• Depth: 50mm = 0.05m
• Volume: 10 × 0.05 = 0.5m³
• Weight: 0.5 × 1.6 = 0.8 tonnes

Common Aggregate Types and Densities

• MOT Type 1 (sub-base): ~1.6–1.8 tonnes/m³
• 20mm gravel: ~1.7 tonnes/m³
• 10mm shingle: ~1.6 tonnes/m³
• Sharp sand: ~1.6 tonnes/m³
• Ballast (all-in): ~1.8 tonnes/m³
• Scalpings: ~1.5 tonnes/m³

Typical Depth Requirements

• Driveway sub-base: 100–150mm compacted
• Patio sub-base: 75–100mm compacted
• Pipe bedding: 100mm below + 100mm above pipe
• Soakaway fill: Full depth of pit
• Footpath: 50–75mm compacted

Compaction Allowance

Loose aggregate compacts by approximately 20–25% when vibrated or rolled. If you need 100mm compacted depth, order enough for 120–125mm loose depth. Our calculator accounts for this automatically.

Ordering Tips

• Bulk bags (850kg–1 tonne): Most common delivery unit. Easy to place with a crane lorry.
• Loose/tipped: Cheapest per tonne for 3+ tonnes. Needs clear access.
• 25kg bags: Convenient for small jobs but 3–4× the cost per tonne.

Always add 5–10% extra to account for uneven ground, slight over-depth, and wastage.