Free tool
Is It Worth Stocking This Spare Part?
Enter your spare part data and get a clear recommendation — stock it, or order on demand.
Spare part data
Downtime impact
Result: spare part stocking recommendation
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Request a spare parts strategy consultationHow the calculation works
The recommended stock is calculated as: rounded-up (failures per year × lead time in days ÷ 365), i.e. the expected number of failures during one lead time. Holding cost = part price × 15% (a typical assumption for carrying cost) × quantity. Risk cost = failures per year × lead time × 24 h × downtime cost per hour. If the risk cost exceeds the holding cost, the tool recommends keeping the part in stock; otherwise, order on demand.
Example: a part costs EUR 450, lead time 21 days, 0.5 failures a year and downtime of EUR 200/h. The recommended quantity is 1, the holding cost EUR 68 and the risk cost EUR 50,400 – so keep it in stock.
Frequently asked questions
Why is a 15% carrying cost used?
It is a common typical assumption for carrying cost (capital, space, obsolescence). For a more precise estimate, use your own company’s figures.
How do I estimate the lead time?
Ask the supplier for a realistic lead time including transport and customs, and prefer a conservative value.
What if there have been no failures before?
Use the manufacturer’s MTBF or an expert estimate. A very low frequency gives a low risk cost.
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