OEE Lab / Spare Parts Inventory Cost Calculator

What does your spare-parts storeroom really cost?

A storeroom costs you twice: the carrying cost of every part you hold, and the downtime cost of the critical part you did not. Most plants pay both at once, overstocked on slow movers and short on the spare that stops the line. Enter your numbers and see the real annual total. Numbers update as you type.

Your storeroom

Use your total MRO inventory value and the critical stockouts that actually stopped production.

Total value of spares on the shelf.
%
Capital, storage, obsolescence, shrinkage (often 20-25%).
Times a missing part stopped a line.
h
Line down until the part arrives.
Lost margin plus fixed cost while the line is stopped.
What the storeroom costs you - every year
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Carrying cost plus stockout downtime cost.
all carrying50 / 50all stockout
Carrying cost / yr
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Stockout cost / yr
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Downtime hours lost / yr
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Stockout share of cost
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Carrying vs stockout

Your numbers appear here.

Get the one-page storeroom cost breakdown for your plant

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Put a real number on the parts you wait for.

The stockout side of this cost is invisible until you log it. The free OEE Tracker captures every stop and its reason, so waiting-for-a-part downtime stops disappearing into general breakdown time and shows up where you can act on it.

Open the free OEE Tracker
Free, and your data stays yours.

Stock the parts that stop the line, not the ones that sit.

Fabrico links every spare to the asset it serves and sets min and max levels by criticality, so the part for a critical bottleneck is on the shelf and the dead stock is not. Less capital on the floor, and fewer lines down waiting for a part that should have been there.

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The storeroom is a hidden cost centre

Spare parts feel like insurance, so they rarely get challenged. But every part on the shelf ties up capital, takes space, and can go obsolete before it is used, and the parts you skipped to save money are the ones that leave a line down for a shift. The two costs pull in opposite directions, which is why cutting inventory blindly raises stockout risk, and stocking everything blows the carrying cost. The goal is not less stock or more stock, it is the right stock.

The math

Carrying cost = inventory value times the annual carrying rate. Stockout cost = critical stockouts per year times hours waiting per stockout times downtime cost per hour. Total storeroom cost = carrying cost plus stockout cost. The stockout share tells you which way your storeroom is out of balance.

What carrying rate should I use?

A common estimate is 20 to 25 percent of inventory value per year, covering capital, storage, insurance, obsolescence and shrinkage. Use the figure your finance team applies if you have one.

How do I know my critical stockouts?

Count the times in the last year a job waited on a part that was not in stock and a line or asset was down for it. If you do not track it, that is the first fix, and the free OEE Tracker captures the reason on every stop.

How do we right-size the storeroom?

Set min and max levels from each part's link to asset criticality, not from habit. Protect the spares for critical bottleneck assets, and let the slow-moving just-in-case stock fall. The CMMS ROI calculator shows the payback, and Fabrico is how it gets managed.

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