How do you calculate stockpile days of cover?

Divide usable stockpile tonnage by daily draw-down to get unprotected days, then apply your safety factor for the protected figure. With 12,500 tons and 850 tons/day, that is about 14.71 unprotected days, reducing to about 12.25 once a 1.2x safety factor is applied.

What does the safety factor do here?

It shrinks the raw days of cover to a conservative buffer so you reorder before truly running dry. A 1.2x factor takes the 14.71 unprotected days down to roughly 12.25 protected days.

What is usable stockpile volume versus total volume?

Usable inventory excludes the dead base of the pile, material below reclaim level, and any reserved or quarantined stock. Plan on usable tons, since the rest cannot actually be drawn down.

How much stockpile cover should I keep?

It depends on lead time and supply reliability, but a common rule is to hold enough protected cover to outlast your longest realistic delivery gap plus a margin. Set the safety factor so protected days comfortably exceed that gap.

Why is my pile running out faster than calculated?

Usually because actual draw-down exceeded the steady rate you entered, the usable tonnage included unreclaimable dead stock, or weather and access problems compressed the effective supply window.

Days of cover vs reorder point: what's the difference?

Days of cover is how long current stock lasts; the reorder point is the tonnage at which you must replenish to avoid stockout. Use the protected days figure to set a reorder point that respects your supply lead time.

Bulk Solids, Mining, Aggregates & Material Processing calculator

Stockpile Volume Calculator

Stockpile Volume turns a pile's usable tonnage and its daily draw-down into a days-of-cover figure, then applies a safety factor so you plan against a protected buffer rather than the raw number. Site planners, logistics coordinators, and plant managers at quarries, mines, ports, and material yards use it to decide when to replenish before a pile runs short. It matters because running a stockpile to zero stalls the whole downstream operation, while over-stocking ties up cash and yard space and risks weathering or segregation. A single days-of-cover number, hedged with a safety factor, makes reorder timing defensible.

What this calculator does

Estimate stockpile volume for stockpile volume for bulk solids, mining, aggregates, and material processing using plant-floor material, production, quality, capacity, or cost inputs.
a plant team is reviewing stockpile volume for bulk solids, mining, aggregates, and material processing and needs a clear stockpile volume for production, quality, capacity, maintenance, purchasing, or costing decisions
It converts usable stockpile tonnage and daily draw-down into days of cover, and applies a safety factor to report a protected buffer alongside the raw unprotected days.

Formula used

Stockpile Volume uses the entered stockpile volume for bulk solids, mining, aggregates, and material processing values on a consistent unit basis.

Inputs explained

Usable stockpile inventory:
Daily stockpile draw-down:
Stockpile cover safety factor:

How to use the result

Use it for reorder and replenishment planning, contingency checks before a supply disruption, or sizing how much pile you need to ride out a delivery gap.
It assumes a steady daily draw-down; seasonal demand swings, weather-related access loss, or a sudden production ramp can burn through the pile faster than the constant-rate figure suggests.

Common questions

How do you calculate stockpile days of cover? Divide usable stockpile tonnage by daily draw-down to get unprotected days, then apply your safety factor for the protected figure. With 12,500 tons and 850 tons/day, that is about 14.71 unprotected days, reducing to about 12.25 once a 1.2x safety factor is applied.
What does the safety factor do here? It shrinks the raw days of cover to a conservative buffer so you reorder before truly running dry. A 1.2x factor takes the 14.71 unprotected days down to roughly 12.25 protected days.
What is usable stockpile volume versus total volume? Usable inventory excludes the dead base of the pile, material below reclaim level, and any reserved or quarantined stock. Plan on usable tons, since the rest cannot actually be drawn down.
How much stockpile cover should I keep? It depends on lead time and supply reliability, but a common rule is to hold enough protected cover to outlast your longest realistic delivery gap plus a margin. Set the safety factor so protected days comfortably exceed that gap.
Why is my pile running out faster than calculated? Usually because actual draw-down exceeded the steady rate you entered, the usable tonnage included unreclaimable dead stock, or weather and access problems compressed the effective supply window.

Last reviewed 2026-05-12.