Definition
Lead time is the elapsed time from the moment a purchase order is placed on a supplier to the moment goods are received and available in inventory. It includes order processing time (supplier confirmation), manufacturing or pick-pack time, transit time, and receiving processing time. Lead time is one of the two primary inputs (along with demand variability) that determine required safety stock — longer lead times require more safety stock to maintain the same service level. Supply chain managers track lead time by supplier and SKU, and monitor lead time variability (how much the actual lead time deviates from the average) separately because variability has a larger impact on safety stock than average lead time.
Why It Matters
Lead time directly determines how much inventory you must carry. A supplier with a 30-day average lead time requires twice the safety stock of a supplier with a 15-day lead time, assuming the same demand variability and service level target. Reducing lead time — through supplier development, nearshoring, or logistics network changes — is often the highest-ROI inventory reduction lever available. Inventory Optimization Tool →
Frequently Asked Questions
What is lead time in supply chain?
Lead time is the total elapsed time from placing a purchase order to receiving usable inventory. It includes supplier processing time, manufacturing or sourcing time, packaging, transit, customs clearance (for imports), and receiving at your facility. It is the primary driver of how much inventory you need to hold.
What is lead time variability?
Lead time variability is the standard deviation of actual lead times around the average. A supplier with an average 14-day lead time that sometimes delivers in 10 days and sometimes in 20 days has high variability. High variability requires more safety stock than a stable lead time because you must buffer against the worst-case scenarios, not just the average.
How do you reduce supplier lead time?
Reduce supplier lead time by: improving order forecasting shared with the supplier (enabling pre-positioning), paying for finished goods inventory held at the supplier's facility (VMI), qualifying nearshore suppliers as alternates, negotiating service-level agreements with lead time penalties, and improving your own PO issuance lead time.