| Scenario | Method | Inputs | Bank (m³) | Loose (m³) | Compacted (m³) |
|---|---|---|---|---|---|
| Borrow Pit A | Rectangular | 25 m × 12 m × 2.5 m, swell 20%, shrink 10% | 750.000 | 900.000 | 675.000 |
| Borrow Pit B | Side-slope | 20 m × 10 m bottom, depth 2.5 m, slope 1.5:1 | ~804.167 | ~965.000 | ~723.750 |
| Borrow Pit C | Average end area | A1 120 m², A2 160 m², distance 30 m | 4,200.000 | 5,040.000 | 3,780.000 |
- Rectangular / Prismatic: V = L × W × D
- Side-slope pit (frustum): compute bottom area A1 and top area A2, then V = h/3 × (A1 + A2 + √(A1×A2))
- Average end area: V = ((A1 + A2) / 2) × L
- Loose volume (swell): V_loose = V_bank × (1 + swell/100)
- Compacted volume (shrink): V_compacted = V_bank × (1 − shrink/100)
- Truck loads: loads = ceil(V_loose / capacity)
- Choose a method that matches your borrow geometry and survey data.
- Select your input units, then enter measurements carefully.
- Add swell and shrink factors if you need conversion volumes.
- Optionally enter truck capacity to estimate haul trips.
- Press Calculate to show results below the header.
- Use the CSV or PDF buttons to export latest or history.
Borrow volume and pay quantities
Borrow volume is commonly tracked as bank volume because it reflects in-place material before excavation. Estimating bank volume supports borrow approvals, cut-fill balancing, and payment checks. This calculator reports bank, loose, and compacted volumes so you can translate survey geometry into hauling and placement quantities. Conversions to cubic yards and cubic feet help align vendor quotes, equipment logs, and site diaries.
Selecting a field method
Different surveys produce different inputs. The rectangular method fits stock-like prisms, test pits, and uniform trenches. The side-slope pit option models a frustum where top dimensions increase with depth and slope, matching many borrow pits and temporary excavations. Average end area is useful when you have two cross sections and the interval distance, such as along a haul road widening or drainage channel borrow.
Swell and shrink factors
Material rarely keeps the same volume through the workflow. Swell increases volume after excavation due to loosening; typical ranges are about 10–35% depending on gradation and moisture. Shrink reduces volume after compaction and trimming; typical ranges are about 5–20% based on density targets and lift control. Use lab Proctor results, field density tests, or contract specifications to justify your chosen factors.
Haul planning and truck loads
Haul estimates are most realistic when based on loose volume because trucks carry loosened material. Enter a truck capacity in cubic meters and the calculator rounds loads up to the next whole trip. For example, 1,250 m³ loose with a 10 m³ tipper suggests 125 loads. Pair this with cycle time, route length, and queuing to plan shifts, fuel, and spotter coverage.
Quality control and reporting
A repeatable calculation sheet reduces disputes. Save runs by project section, keep timestamps, and export CSV for spreadsheets or PDF for submittals. Compare compacted volume with placement areas and design thickness to validate that delivered material matches planned layers. When survey updates arrive, rerun the method with new geometry and keep the history to show the progression of quantities.
FAQs
How is bank volume different from loose volume?
Bank volume is in-place material before excavation. Loose volume applies swell to reflect the larger volume after digging and loading. Use bank for pay quantities and loose for hauling and stockpiling estimates.
When should I use the side-slope pit method?
Use it when the excavation widens toward the top and you know bottom dimensions, depth, and side slope. It models a tapered pit using bottom and top areas, which suits many borrow pits and temporary cuttings.
Do I need swell and shrink factors?
No. Set them to zero if you only need geometric bank volume. Add swell to estimate trucked quantity, and add shrink to estimate compacted placement. Always align factors with contract definitions and test data.
Can I enter feet and still get metric outputs?
Yes. Enter lengths or areas in feet or square feet, and the calculator converts internally to cubic meters. It also displays cubic yards and cubic feet to support mixed-unit subcontractor quotes and equipment logs.
How are truck loads calculated?
Loads are computed as the loose volume divided by truck capacity, then rounded up to the next whole trip. If capacities vary, run several scenarios or use an average effective capacity based on real payload tickets.
Will my saved runs remain after I leave the page?
Saved runs are kept in your current browser session. They usually persist while the tab or browser remains open, but they may clear after a restart depending on settings. Export CSV or PDF for long-term records.