Topsoil Calculator
Calculate how many cubic metres and tonnes of topsoil, garden soil or turf underlay you need for any lawn or garden area. Get delivery quantities and cost estimate instantly.
🔨 Topsoil Calculator
📐 How It Works
Topsoil volume is calculated the same way as any fill material — area multiplied by depth. Add 10% for compaction and settling. Topsoil is sold by the cubic metre (loose) or by the tonne. The relationship between volume and weight depends on soil type and moisture content.
📋 Worked Example
New lawn area 15m × 8m at 150mm depth: Volume = 18 m³. With 10% waste = 19.8 m³. At 1.2 t/m³ topsoil density = 23.8 tonnes. At $90/m³ = $1,782.
❓ Frequently Asked Questions
Minimum 100mm of quality topsoil for lawn establishment. 150mm is better for a healthy established lawn. Poor existing soil or sloping sites: 200mm. New construction sites often have compacted or poor subsoil — always test the existing soil before deciding on topsoil depth.
Topsoil is generally screened natural soil. Garden mix is a blend of topsoil, compost and often sand or other amendments — better for garden beds. Screened topsoil is suitable for lawns and filling. Garden mix has better water retention and nutrient content for planting.
Small tipper: 3–5 m³. Medium tipper: 6–8 m³. Large semi-trailer: 20–25 m³. Bulk bags (1 tonne bags): 0.6–0.8 m³ each. For areas over 10 m³, a tipper delivery is more economical than bulk bags.
Yes — scarify or cultivate the existing ground to 50–75mm depth before laying topsoil. This breaks the interface between old and new soil, improving drainage and root penetration. Remove weeds, rocks and debris. Grade to desired levels before topsoil application.