TryBuildCalcFoundation Excavation Calculator (Earthwork Volume, Truck Loads & Cost)
Calculate excavation volume, loose soil, truck loads, and cost.
Estimate foundation excavation quantity, loose soil, truck loads, and cost for rectangular building foundation areas. Adjust dimensions, units, quantity, swell factor, truck capacity, and rate to match your site.
🕒 Last updated: July 30, 2026
Inputs
ℹ️Typical: 10–40% (Sand ~15%, Clay ~30%, Rock ~60%)
ℹ️Used only to convert volume into an approximate weight in tons — does not affect volume, swell, or cost.
ℹ️Typical: 3-10 m³ per trip (about 105-350 cft per trip)
ℹ️Optional buffer added on top of the base cost for unexpected site conditions — commonly 5-15%.
You need approximately 144.000 m³ (~230.40 t) of excavation, requiring 24 truck loads and costing around ₹50,400.
Calculations
Excavation Volume: 115.200 m³ (~184.32 t)
Loose Volume: 144.000 m³ (~230.40 t)
Swell Added: +28.80 m³ (~46.08 t)
Estimates
Truck Loads: 24
Estimated Cost: ₹50,400
Approximate results for planning only. Verify with a professional.
Looking for the verification checklist, reference tables, or tips and mistakes?See the complete Rectangular Excavation Calculator.
Foundation excavation calculation
This page is pre-filled for a 12 m x 8 m x 1.2 m building foundation excavation — a 115.2 m³ bank volume that becomes 144 m³ of loose soil after a 25% swell allowance.
At a 6 m³ truck capacity, that's 24 truck loads, costing an estimated 50,400 at 350 per m³ applied to the loose volume.
- Foundation: 12 m x 8 m x 1.2 m.
- Bank volume: 115.2 m³.
- Loose volume: 144 m³, 24 truck loads.
How does excavation volume calculation work?
Excavation calculation involves determining the in-situ (original) soil volume, adjusting it for swell, and estimating transportation and cost requirements.
Step 1 — Calculate Excavation Volume
Total Volume = Volume × Number of Units
If sections differ in size: Total Volume = Sum of (Length × Width × Depth × Count) for every section
This gives the in-situ (original) volume of soil before excavation. All dimensions must be converted into meters. If you have several identical excavations (e.g. 5 matching footings), use the Number of Units multiplier. If your excavations are different sizes(e.g. 4 small footings plus 2 larger ones), switch on "Multiple Different-Sized Excavations" and enter each size as its own section — the calculator sums every section's volume into one total automatically.
Step 2 — Apply Swell Factor
Soil expands after excavation due to loosening. This increase is called swell and depends on soil type:
- Sand / Gravel → ~10–20%
- Ordinary / Mixed Soil → ~20–30%
- Clay → ~20–40%
- Rock → ~50–80%
Step 3 — Calculate Truck Loads
If Truck Capacity is entered in cft: Truck Capacity (m³) = Truck Capacity (cft) ÷ 35.3147
This helps estimate how many trips are required to transport excavated soil from the site. Truck capacity can be entered directly in m³, or in cft (cubic feet) if that's how your vehicle or contractor quotes it — the calculator converts cft to its m³ equivalent first, then applies the same formula, so the result is identical either way.
Step 4 — Estimate Excavation Cost
If Cost is entered per cft: Cost per m³ = Cost per cft × 35.3147
Cost depends on soil type, labor, machinery, and site conditions. The cost rate can be entered per m³ or per cft — a cft rate is converted to its m³-equivalent rate before multiplying, since a cft rate is naturally a smaller number for the same total budget (1 m³ = 35.3147 cft).
Step 5 — Add Contingency (Optional)
Total Cost = Base Cost + Contingency Amount
Contingency is an optional buffer on top of the base cost to cover unexpected site conditions — hidden obstructions, unforeseen rock, weather delays, or price fluctuations. It defaults to 0%; a commonly used range is 5-15% depending on how well the site conditions are already known.
Example excavation calculation
This example uses the active calculator inputs above and follows the same steps from the formula section — showing the default scenario if you haven't changed anything, or your own live inputs once you do.
Input Values Used
| Input | Value | Why it is used |
|---|---|---|
| Dimensions | 12 m × 8 m × 1.2 m | Sets the in-situ excavation volume |
| Number of units | 1 | Multiplies volume for repeated identical excavations |
| Swell factor | 25% | Converts in-situ volume into loose (haulage) volume |
| Equipment & cost | 6 m³/trip, ₹350 per m³ | Sets truck loads and total cost |
Step 1 — Calculate Excavation Volume
| Calculation | Substitution | Result |
|---|---|---|
| Volume per unit | 12 × 8 × 1.2 | 115.200 m³ |
| Total volume | 115.200 × 1 | 115.200 m³ |
Step 2 — Apply Swell Factor
| Calculation | Substitution | Result |
|---|---|---|
| Loose volume | 115.200 × (1 + 25/100) | 144.000 m³ |
Step 3 — Truck Loads & Cost
| Calculation | Substitution | Result |
|---|---|---|
| Truck loads | 144.000 ÷ 6.00 m³ | 24 trucks |
| Base cost | 144.000 × rate | ₹50,400 |
| Total cost | Base cost | ₹50,400 |
Therefore, this excavation needs approximately 144.000 m³ of loose soil, requiring 24 truck loads and costing around ₹50,400.
This page keeps things focused on the calculation above. For the full construction guide — verification checklist, reference tables, usage steps, tips, common mistakes, and limitations.See the complete Rectangular Excavation Calculator.