Spare Parts Min-Max vs Reorder Point: Two Ways to Never Run Out (or Overstock)

Key takeaways

• Min-max keeps stock between a floor (min) and ceiling (max), ordering up to max.
• Reorder point triggers an order of a fixed quantity when stock hits a threshold.
• Min-max suits variable demand; reorder point suits steady demand with known lead time.
• The wrong method on a critical spare means stockout-driven downtime or tied-up cash.

Short answer: Min-max replenishment orders enough to reach a maximum whenever stock falls to a minimum. Reorder point triggers a fixed-quantity order when stock hits a calculated threshold (demand during lead time plus safety stock). Min-max flexes with variable demand; reorder point is simplest for steady demand. On critical spares, the choice decides between stockouts and overstock. See also why asset tags matter more than people think.

How min-max works

• Floor (min) and ceiling (max) per part.
• When stock hits min, order up to max.
• Order quantity varies.

How reorder point works

• Threshold = demand over lead time + safety stock.
• Hit the threshold, order a fixed quantity (often EOQ).
• Predictable order sizes.

Choosing between them

Steady, predictable usage with stable lead time: reorder point is clean. Lumpy or seasonal demand: min-max adapts better. Criticality decides safety stock either way.

Why criticality drives it

A cheap, fast-to-source part can run lean. A critical, long-lead spare whose absence stops the line needs generous safety stock regardless of method — the downtime cost dwarfs the carrying cost.

How this protects uptime

Spare-parts availability is a reliability control: the right part on the shelf turns a multi-day wait into a same-shift repair, directly protecting Availability and OEE.

See how Fabrico captures this automatically on your lines — explore OEE for manufacturing or book a demo.

Related reading

• why asset tags matter more than people think
• condition based vs time based maintenance
• cycle counting vs physical inventory

Frequently asked questions

Which method is better?

Neither universally — match to demand pattern and lead time.

Where does safety stock come in?

It cushions both methods against variability.

How does criticality factor in?

It sets safety stock and service level for the part.

Does this affect OEE?

Yes — stockouts extend downtime and cut Availability.