Excavation and fill calculator
Free excavation and fill calculator: rectangular or sloped pit volume, swell/bulking, compacted-fill loose material and truck trips. No sign-up.
How are excavation and fill volumes calculated?
Earthworks use three volumes: in-situ (bank) cut, bulked loose haulage volume, and compacted fill. Treating them as equal breaks truck and material plans. This tool uses rectangular or frustum geometry, then applies swell/shrink and truck fill ratio.
Steps
- Choose excavation or fill.
- Pick rectangular or sloped (bottom–top) geometry.
- Enter length, width, depth/thickness and any deducted volume.
- Set soil shortcut or your own swell/shrink percentage.
- Read truck trips from nominal capacity × fill ratio.
Formulas
Rectangular volume = L × W × D. Sloped frustum = D/3 × (A1 + A2 + √(A1×A2)). Net bank = gross − deduct. Loose haul = net × (1 + swell%/100). Loose fill needed = compacted ÷ (1 − shrink%/100). Trips = ceil(volume ÷ (capacity × fill%)).
Guidance swell ranges
There is no single correct percentage—use lab/spec data when available:
| Soil | Swell (approx.) | Note |
|---|---|---|
| Sand | 10–15% | Easy dig, lower swell |
| Gravel | 5–15% | Granular |
| Clay | 20–40% | Depends on moisture/PI |
| Mixed fill | 20–30% | Default shortcut ≈ 25% |
| Rock / blasted | 50–80% | Measure on site |
Worked examples
Use these to verify the tool; replace with your dimensions.
- 10 × 8 × 2 m cut, 25% swell, 20 m³ truck × 90% fill → 160 m³ bank, 200 m³ loose, 12 trips (~16 m³ spare on last trip).
- Same plan, 0.50 m compacted fill, 20% shrink loss → 40 m³ compacted, 50 m³ loose, 3 trips.
- Bottom 10×6, top 12×8, depth 2.5 m, qty 2, 20% swell → ≈386.5 m³ bank, ≈463.8 m³ loose.
Practical tips
- Trips are volume-based; legal axle weight may force smaller loads.
- Slope angle/shoring are not designed here—take top sizes from geotech.
- Do not reuse the same % for swell and shrink.
- Use deducted volume for existing voids or prior excavation.
Application note
Planning estimate only. Not a substitute for soil investigation, slope/shoring design or contract measurement.
Related calculators
For fill tonnage or overall building cost:
Frequently asked questions
How do I calculate excavation volume?
Multiply L × W × average depth (or use the frustum formula for sloped pits). Apply swell for haul volume and divide by effective truck capacity for trips.
What is bulking / swell?
Soil gains volume when excavated. Loose = bank × (1 + swell%/100). Clay usually swells more than sand.
How are truck trips calculated?
ceil(haul m³ ÷ (nominal m³ × fill ratio)). Check legal weight separately.
How much loose material for fill?
loose = compacted ÷ (1 − shrink%). Example: 40 m³ target at 20% loss → 50 m³ loose.
Rectangular vs sloped mode?
Rectangular assumes vertical sides. Sloped mode uses different top/bottom plan areas via the frustum formula.
Does this design slopes or shoring?
No—only geometric volume and haul/fill planning.