Excavation Calculator

Calculate the volume of soil to excavate for any foundation, trench, pool or earthworks project. Get cubic metres, truck loads and cost estimate instantly. Works for bulk excavation and trenching.

Quick answer: Excavation Volume = Length × Width × Depth. Soil expands 20–30% when excavated (bulking factor). A 5m × 4m × 1m excavation = 20 m³ in-situ but produces 24–26 m³ of spoil to remove.

🔨 Excavation Calculator

Excavation Type

Length (m)

Width (m)

Depth (m)

Soil Type

Truck Size (m³)

Excavation Rate ($/m³)

Optional — machine excavation typically $35–$80/m³

Excavation Volume

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Spoil to Remove

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Truck Loads

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Estimated Cost

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📐 How It Works

Excavation volume is the in-situ (undisturbed) volume of material removed. When soil is excavated it swells (bulks) by 20–35% depending on soil type. The bulked volume determines how many truck loads are needed for spoil removal.

In-Situ Volume = Length × Width × Depth Spoil Volume = In-Situ Volume × Bulking Factor Truck Loads = Spoil Volume ÷ Truck Capacity

📋 Worked Example

House slab excavation 12m × 10m × 0.4m deep in clay: Volume = 48 m³. Spoil = 48 × 1.25 = 60 m³. At 10 m³ per truck = 6 truck loads. At $55/m³ machine rate = $2,640 excavation cost.

❓ Frequently Asked Questions

When soil is excavated it expands in volume because it loses its compaction. Sandy soil bulks 10–20%, clay 20–30%, heavy clay and rock 30–40%. Always use a bulking factor when calculating spoil removal — the in-situ volume is always less than the truck volume.

Machine excavation in Australia: $35–$60/m³ for bulk excavation in average conditions. Hand excavation: $150–$300/m³. Rock excavation: $200–$500/m³. Spoil removal (truck): $25–$50/m³ additional. Always get quotes for your specific site conditions.

Mini excavator (1–3 tonne): 0.03–0.08 m³ per bucket. Medium excavator (8–20 tonne): 0.3–0.8 m³. Large excavator (20–50 tonne): 0.8–2.5 m³. Productivity depends on soil type, reach and cycle time.

In most Australian jurisdictions, excavations deeper than 1.0m or closer than 2.0m to a boundary require a building permit. Trenching near services requires Dial Before You Dig notification. Always check with your local council before excavating.