Cost per BCM Calculator
Cost per BCM is the unit rate for moving material measured in its bank (in-situ) state: Cost per BCM = total cost ÷ bank cubic metres.
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How to use this calculator
- Enter the total cost for the period or activity ($) — include everything you want in the rate (labour, fuel, maintenance, consumables).
- Enter the bank cubic metres (BCM) moved — in-situ (undisturbed) volume, not loose/truck volume.
- Optionally add the in-situ (bank) density in t/BCM to also get tonnes moved and the equivalent cost per tonne.
How it works
Cost per BCM is the unit rate for moving material measured in its bank (in-situ) state: Cost per BCM = total cost ÷ bank cubic metres. BCM is the standard volume basis in open-pit mining and bulk earthworks because it maps directly to the surveyed pit volume, unlike loose cubic metres (LCM) which swell after digging. Keep the cost and the volume over the same scope and period so the rate is meaningful.
If you supply an in-situ (bank) density in tonnes per BCM, the tool converts volume to mass (tonnes = BCM × density) and reports the equivalent cost per tonne (total cost ÷ tonnes). This lets you compare a volume-based dig rate against tonnes-based reconciliation and OEM cost-per-tonne models. Typical bank densities are roughly 1.6–2.0 t/BCM for coal/soft rock and 2.2–2.7 t/BCM for hard rock overburden — use your own tested value.
Worked example
Overburden dig-and-haul unit rate. A truck-and-shovel fleet moved 42,000 BCM of overburden last month at a total cost of $250,000 (labour, fuel, maintenance and consumables). Cost per BCM = 250,000 ÷ 42,000 = $5.95 /BCM. Entering an in-situ density of 2.4 t/BCM also gives 100,800 t moved and a cost of $2.48 /t — the two rates that reconciliation and OEM cost models are usually reported against.
Common mistakes
- Mixing volume bases — dividing cost by loose cubic metres (LCM) or truck-tallied volume instead of bank cubic metres (BCM). LCM is inflated by swell, so it understates the true cost per BCM. Use the surveyed in-situ volume.
- Leaving costs out of the total — a rate built only on fuel or only on hire understates the real cost. Decide the scope (e.g. all direct fleet costs) and use the same scope every period so rates are comparable.
- Using a loose or generic density for the cost-per-tonne cross-check. The density here must be the in-situ (bank) density in t/BCM; a loose density will give the wrong tonnes and a wrong cost per tonne.
Frequently asked questions
What is a BCM in mining?
A BCM is a bank cubic metre — one cubic metre of material measured in place, before it is dug and loosened. It is the standard volume unit for open-pit mining and bulk earthworks because it matches the surveyed pit or bench volume. After excavation the same material swells into more loose cubic metres (LCM), which is why cost rates should be quoted per BCM, not per loose or truck volume.
How do I get cost per tonne from cost per BCM?
Multiply BCM by the in-situ (bank) density (t/BCM) to get tonnes, then divide total cost by tonnes. This tool does that automatically when you enter a density: for example 42,000 BCM at 2.4 t/BCM is 100,800 t, so $250,000 becomes $2.48 per tonne alongside $5.95 per BCM.
Which costs should I include in the total?
Include whatever you want the unit rate to represent — commonly all direct fleet costs (operator labour, fuel, tyres, ground-engaging tools, maintenance and consumables), sometimes plus an allocation of overheads. The key is to fix the scope and apply it consistently so period-to-period rates are comparable. This is an estimate for planning and reconciliation, not a replacement for site cost accounting.
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