Cut-to-Fill Balance Calculator
Balance earthworks cut against fill. Enter the available cut (bank/in-situ) volume and the required compacted fill volume, plus swell and shrinkage factors, and the tool tells you how much bank material the fill actually needs, whether the site has a surplus to export or a deficit to import, and the loose (truck) volume for haulage.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the cut volume as bank/in-situ cubic metres and the fill volume as the COMPACTED cubic metres required.
- Adjust the swell factor (bulking of excavated material, default 25%) and the shrinkage factor (compaction loss of fill, default 10%) to suit your material.
- Read the bank material needed for the fill, the surplus or deficit, and the loose haul volume for truck counts.
How it works
Compacted fill is denser than bank material, so placing Vfill compacted requires Vfill / (1 − shrink/100) of bank material (10% shrinkage → about 11% more bank). The balance is the available cut minus that bank requirement: a positive balance is surplus bank to export, negative is a deficit to import. Excavated material also bulks when loosened for hauling, so the loose (truck) volume of the surplus or deficit is |balance| × (1 + swell/100) (25% swell → 25% more loose volume). Bank, compacted and loose are three different measures of the same material, and swell/shrinkage convert between them.
Worked example
Worked example. With 10,000 m³ of cut (bank) and 8,000 m³ of required compacted fill at 10% shrinkage, the fill needs 8,000 / 0.9 = 8,888.9 m³ of bank material. That leaves a surplus of 10,000 − 8,888.9 = 1,111.1 m³ of bank to export, which at 25% swell is 1,111.1 × 1.25 = 1,388.9 m³ of loose material to haul away.
Common mistakes
- Entering the fill as a loose or bank volume — it must be the COMPACTED (in-place) volume, since shrinkage is applied to convert it back to bank.
- Comparing cut and fill directly without shrinkage — because compacted fill needs more bank than its compacted volume, ignoring shrinkage understates the material required.
- Using the bank balance for truck counts — trucks carry loose (bulked) material, so apply the swell factor to get the haul volume.
Frequently asked questions
What is the difference between swell and shrinkage?
Swell (bulking) is the volume increase when in-situ (bank) material is excavated and loosened for hauling. Shrinkage is the volume decrease when material is placed and compacted as fill, ending up denser than bank. Both are expressed as percentages of the bank volume.
What do surplus and deficit mean?
Surplus means the cut provides more bank material than the fill needs, so the extra must be exported (spoiled off site). Deficit means the cut is short of the fill requirement, so additional bank material must be imported. The tool also gives the loose volume of that surplus or deficit for haulage planning.
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