LHD Bucket Fill Factor Calculator

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Enter Values

Actual bucket load volume

Rated bucket capacity

Loose muck density (t/m³, optional)

Enter your values and press Calculate to see results.

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 actual volume of muck carried in the bucket (from a load survey, weightometer back-calculation, or estimate) in cubic metres.
Enter the manufacturer's rated (heaped) bucket capacity in cubic metres.
Optionally add the loose (broken) muck density in t/m³ to also get the payload tonnes carried per pass.

How it works

Bucket fill factor is the ratio of the volume of material actually carried to the manufacturer's rated heaped bucket capacity, expressed as a percentage: fill factor = actual load volume ÷ rated capacity × 100. It is a core loading-efficiency metric for underground LHD (scooptram / load-haul-dump) fleets and feeds directly into cycle-time and daily-tonnes production models.

When a loose muck density is supplied, the payload carried per pass is estimated as payload = actual load volume × density (tonnes). Note this uses the loose/broken density of the muck pile, not the in-situ solid rock density. Fill factor depends heavily on fragmentation, floor condition, operator technique and bucket geometry, so treat computed values as planning estimates and confirm against measured haulage data.

Worked example

6.5 m³ scooptram carrying 5.2 m³ of muck. A load-haul-dump (LHD) unit rated at 6.5 m³ heaped capacity is carrying an actual measured load of 5.2 m³. Fill factor = 5.2 ÷ 6.5 × 100 = 80.0%. With a loose muck density of 2.0 t/m³, payload per pass = 5.2 × 2.0 = 10.4 t. An 80% fill factor is typical for coarse blasted development muck — improving fragmentation would lift it toward the rated bucket.

Common mistakes

Using in-situ (solid rock) density instead of the loose, broken muck density — broken muck occupies more volume, so its density is lower and using the solid figure overstates payload.
Mixing struck and heaped capacities: the rated capacity should be the heaped rating you are comparing against, otherwise the fill factor is not meaningful.
Entering the actual volume and rated capacity in different units (e.g. one in cubic yards) — both must be cubic metres for the percentage to be correct.

Frequently asked questions

What is a good bucket fill factor for an LHD?

It depends on the material and conditions. Well-fragmented, free-flowing muck on a clean floor can approach or exceed 100% (a well-heaped bucket), while coarse, poorly-blasted development muck often loads at 70–90%. Persistently low fill factors point to fragmentation, digability or operator-technique issues worth investigating.

Can the fill factor exceed 100%?

Yes. The rated capacity is a nominal heaped rating, so a generously heaped bucket in easy-digging, fine material can carry more than the rated volume, giving a fill factor above 100%. Very high values (well over 130%) usually mean the inputs are in mismatched units and should be checked.

How does fill factor affect production?

Payload per pass scales directly with fill factor, so a fleet loading at 75% instead of 90% moves materially fewer tonnes per cycle. Fill factor is therefore a key lever in LHD cycle-time and daily-production models alongside cycle distance, speed and availability.

Tip: Enter any known values to calculate the remaining results.

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