Inventory glossary
What is Supplier lead time variability?
Supplier lead time variability is how much a supplier's actual delivery time swings around their average lead time.
High lead time variability is riskier than a long but steady lead time. If you know a supplier always takes exactly 30 days, you can plan around it. If they take anywhere from 15 to 45 days, you need extra safety stock to cover the slow months, even though their average looks fine on paper.
Track actual delivery dates against promised dates for each supplier over several orders. If the gap keeps growing or shrinking unpredictably, raise your safety stock for that supplier's SKUs or look for a backup supplier. Suppliers with steady, predictable lead times let you run leaner inventory overall.
Example
A candle store orders from Supplier A every month. Over six orders, delivery took 14, 16, 15, 14, 17, and 15 days. That is tight and predictable, average 15 days. Supplier B promises the same 15 days but delivered in 10, 22, 12, 25, 14, and 20 days. Same average lead time, but Supplier B forces the store to hold more buffer stock because any single order could take 25 days instead of 15.
Common mistakes
- Judging a supplier only on their average lead time and ignoring the spread of actual delivery dates.
- Not recording the actual delivery date for each order, so variability never gets measured.
- Setting the same safety stock for every supplier regardless of how reliable their delivery history is.
Supplier lead time variability and SteadyShelf
SteadyShelf uses each supplier's lead time to set order-by dates per SKU, so a store can flag suppliers whose deliveries run late or early and adjust order timing for those SKUs accordingly.
SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.
Related terms
Lead time · Lead time demand · Safety stock · Supplier scorecard · Demand variability
FAQ
Does a longer average lead time always mean higher risk than a shorter one?
No. A supplier with a 30 day lead time that is always exactly 30 days is easier to plan for than one with a 15 day average that ranges from 5 to 30 days. The spread matters as much as the average.
How can a small store reduce the impact of supplier lead time variability without complex software?
Keep a simple log of promised versus actual delivery dates for each supplier. For suppliers with wide swings, add extra safety stock or order earlier than the stated lead time suggests.
Let SteadyShelf do this math for every SKU
Order-by dates per supplier, seasonal forecasts and draft POs for your Shopify store. $29/month after a 30-day free trial.
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