Bulk Solids, Mining, Aggregates & Material Processing worked example

Stockpile Inventory Days with usable stockpile tonnage on hand of 31,300 tons: a worked example

Push usable stockpile tonnage on hand up to 31,300 tons and the picture changes. This example computes every intermediate figure at that operating point. a plant team is reviewing stockpile inventory days for bulk solids, mining, aggregates, and material processing and needs a clear stockpile inventory days for production, quality, capacity, maintenance, purchasing, or costing decisions

The inputs for this scenario

  • Usable stockpile tonnage on hand: 31,300 tons (raised for this scenario; the documented default is 12,500)
  • Average daily draw from stockpile: 850 tons / day (unchanged)
  • Safety stock multiplier: 1.2 x (unchanged)

Working through the calculation

  • Applying the documented formula (Stockpile Inventory Days uses the entered stockpile inventory days for bulk solids, mining, aggregates, and material processing values on a consistent unit basis.) to the inputs above produces each figure below.
  • At this operating point the engine returns 30.69 tons for stockpile inventory days, the number this scenario is built around.
  • At this operating point the engine returns 36.82 days for unprotected stockpile inventory days.
  • At this operating point the engine returns 31,300 pieces for usable stockpile inventory days inventory.
  • At this operating point the engine returns 850 pieces / day for daily stockpile inventory days usage.

How this compares with the baseline

  • Against the tool's baseline example, where usable stockpile tonnage on hand sits at 12,500 tons and the headline result is 12.25 tons, this scenario comes in 150% above the baseline at 30.69 tons.
  • It computes protected days of cover by dividing usable stockpile tonnage by daily draw and dividing again by the safety factor. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Stockpile Inventory Days: 30.69 tons (headline result)
  • Unprotected stockpile inventory days: 36.82 days
  • Usable stockpile inventory days inventory: 31,300 pieces
  • Daily stockpile inventory days usage: 850 pieces / day

Run it with your numbers

  • Every input above is editable in the live Stockpile Inventory Days calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.