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Backfill Calculator
Estimate backfill material volumes.
Project & Input Data
%
Extra loose material needed to reach the compacted volume — take it from the soils report or a field trial.
%
An editable user-defined allowance — not a universal engineering requirement.
Engineering Assumptions
- A purely volumetric calculation — layer thickness and required density are not addressed.
- The compaction factor is user-entered; no standard soil value is assumed.
- All percentages and inputs are user-defined; the calculation is purely arithmetic and assumes no particular code or specification.
Formula Summary
- Net backfill = max(excavation − structure, 0)
- Compaction volume = net × compaction%
- Waste = (net + compaction) × waste%
- Loose material = net + compaction + waste
Results
Enter your data and press Calculate to see the results.
Engineering Insight
The gap between compacted and loose volume is the most common cause of backfill shortfalls on site; order on the loose volume.
Recommended Action
Confirm the compaction factor with a field trial on the approved material before issuing the supply order.
Next step
This calculator is fully usable as it is. Professional adds saved projects, calculation history and PDF/Excel reports; Premium adds the integrated workflows and the BOQ generator.