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Reorder point formula and safety stock calculator for spare parts
Safety stock z·σ·√L and reorder point of a spare part, Wilson economic order quantity, or Poisson stock for slow movers. Free, no sign-up, instant result.
- Instant result
- Formula and standards shown
- On desktop and phone
Result
45.87uReorder point
- Safety stock
- 9.87u
- Caution : Regular demand assumed (normal law); for a rarely used part, choose "Slow-moving part".
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Reorder point carried over to the part record
Here, the calculator is free and the result is gone when you close the page. In Reglova, it is attached to the work order on the right machine: you find it again at the next breakdown, and on audit day.
The CMMS software comparison, our gaps included- Attached to the work order with its inputs: the server recalculates it, it stays verifiable.
- On the technician's phone, even without a network.
- In the machine's history, for the next breakdown.
- The reorder point is carried over to the part record.
When to calculate a reorder point
01
Set the reorder point of a consumable: filters, belts, common bearings.
02
Decide how many critical spares to keep when they are used once a year.
03
Reduce tied-up capital without more stock-outs.
Good to know
Safety stock assumes steady demand (normal distribution). For a part that is rarely used, choose the “Slow-moving part” calculation (Poisson law).
Reorder point formula, safety stock and EOQ
Three calculations for the spare parts store: the safety stock and reorder point of a part with steady demand; the Wilson economic order quantity, Q* = √(2·D·Cc/(t·Pu)); and, for a slow-moving part, the service level of a given stock under the Poisson law.
Formula · Reference documents
Q* = √(2·D·Cc/(t·Pu)) ; SS = z·σd·√L ; ROP = d·L + SS (d: average daily demand) ; Poisson P(X ≤ s) = Σ e^(−λ)·λ^k/k!
Wilson (1934) ; spare parts inventory management (Poisson law)
Inputs and accepted ranges
| Input | Unit | Accepted range | Example |
|---|---|---|---|
| Calculation | 3 options | Reorder point | |
| Annual demand Dif Calculation: Economic order quantity | u/yr | 0.01 to 1,000,000,000 | |
| Cost per order Ccif Calculation: Economic order quantity | € | 0 to 1,000,000 | |
| Holding rate tif Calculation: Economic order quantity | % | 0.1 to 100 | |
| Unit priceif Calculation: Economic order quantity | € | 0.001 to 10,000,000 | |
| Holding cost per unit (otherwise t × price)if Calculation: Economic order quantity | €/u/yr | 0.0001 to 1,000,000 | Optional |
| Service factor zif Calculation: Reorder point | 0 to 5 | 1.645 | |
| Daily demand standard deviation σdif Calculation: Reorder point | u/day | 0 to 1,000,000 | 2 u/day |
| Lead time Lif Calculation: Reorder point | days | 0 to 3,650 | 9 days |
| Average daily demandif Calculation: Reorder point | u/day | 0 to 1,000,000 | 4 u/day |
| Average demand over lead time λif Calculation: Slow-moving part | 0.0001 to 1,000 | ||
| Stock held sif Calculation: Slow-moving part | 0 to 10,000 | ||
| Target service levelif Calculation: Slow-moving part | % | 50 to 99.999 | Optional |
Calculated results
- Economic order quantity Q*u
- Orders per year
- Reorder pointu
- Safety stocku
- Service level%
- Stock for the target levelu
What the calculator flags
- Regular demand assumed (normal law); for a rarely used part, choose "Slow-moving part".
Reorder points set on each part record in Reglova
- Breakdowns reported by QR code
- Work orders on the phone, even without a network
- Mandatory inspections reminded by email
- Audit file as a PDF, in one click
Free during the beta, no credit card