Home / Guides / Spare parts reorder points
Spare parts reorder points, without the guesswork
A reorder point is the stock level at which you order more. Set it too low and a breakdown waits for a part. Set it too high and money sits on a shelf. The math is simple. Keeping the inputs current is the hard part.
The basic formula
Reorder point = average usage per day x lead time in days + safety stock.
Usage comes from your own consumption history. Lead time is how long the part actually takes to arrive, not what the supplier quotes. Safety stock is the cushion for delays and for demand that comes in bursts.
A worked example (illustrative numbers)
Suppose a bearing is used about once every 30 days and takes 45 days to arrive. Over the lead time you would expect to use 1.5 bearings, so you would order when stock drops to 2 even before any safety stock. If a missing bearing would stop the line, you might hold 3. These numbers are only an example. Use your own history.
Treat critical parts differently
Usage-based math fails for parts that rarely fail but stop production when they do. For those, decide on a minimum to keep on the shelf based on the consequence of not having it and the lead time, not on how often it was used. Mark these parts as critical so a low level gets attention.
Mistakes that cause stockouts
- Reorder points set once and never updated as usage or lead times change.
- Parts taken from the store with no record, so usage looks lower than it is.
- The same part listed under two names, so each looks fine but the total is short.
- Lead time that ignores approval and purchasing time inside your own company.
- No link between a low-stock alert and an actual purchase request.
Keep an audit trail
Every change in quantity should have a reason: received, issued to a job, adjusted after a count. A count that does not match the book is a finding, not an inconvenience, and the movement history is how you find where the gap started.
How Plant Cortex handles inventory
Each part has an on-hand quantity and a reorder point, and every change is logged as a movement with a reason. Stock status is worked out from the current numbers, so it cannot go stale. A low or critical part can start a draft purchase request in one step, and the draft shows which job the part came from. It never orders anything by itself.
General information, not legal advice. Check current regulations and your own site procedures.
Bring us three manuals. See what it answers.
The design-partner pilot is free for sixty days: a handful of your real manuals for one plant. We agree what success means before we start.