Balancing cut and fill, and what happens when the volumes do not match
How excavation, compaction and bulking change the numbers, and why a balanced site is almost never balanced on paper.
The engineering question
The cut volume and the fill volume do not match on the drawings. Is that a mistake, or is it the soil changing volume?
Worked example
The figures below were produced by running the Earthwork Cut and Fill Calculator with the same inputs .
These figures are worked by the published method rather than executed at build time, because this tool is a self-contained page calculator without a programmatic engine.
- Cut in place becomes a larger loose volume once excavated.
- Loose material shrinks again when compacted into the fill.
- The balance is only real if the bulking and compaction factors describe your actual material.
Sanity check
If the site imports material despite a paper balance, the bulking factor is usually too low for a clay that swells.
Tools for this problem
These are the EngiMetric calculators that compute the numbers in this topic. Each one shows its formula, its units and its limits rather than returning a bare result.
- Earthwork Cut and Fill Calculator Estimate site earth movement balance and bulk haulage volumes with swell and shrinkage factors.
- Construction Material Quantity Takeoff Calculator Quantity takeoff for bulk construction materials with wastage: aggregate, sand, cement, and general volume-mass conversions.
References & standards
- BS 6031 — code of practice for earthworks
- UK DMR 3.2 — specification for ground investigation
Related problems
Taking off concrete volumes without mis-ordering the pour
Where concrete volume actually goes — including the parts that are habitually forgotten — and how wastage and batching affect the order.
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