Lead time is the total time that passes between the start of a process and its completion. In supply chain management, it most often refers to the time between placing an order and receiving the goods, whether the order is placed by a customer with a seller or by a company with its supplier.
Lead time is measured in days or weeks for most inventory and procurement decisions, and in hours for fast-moving fulfilment operations.
Why It Matters in Supply Chain
Lead time sets how far ahead a business has to plan. The longer it takes to get stock, the more inventory has to be held to cover demand while waiting for the next delivery.
It directly affects:
- Inventory levels: Longer lead times require higher safety stock and higher reorder points.
- Working capital: More stock on hand or in transit means more cash tied up in inventory.
- Service levels: Unreliable lead times cause stockouts, missed dispatches, and delayed customer orders.
- Production planning: Manufacturers schedule material requirements backward from lead times for each component.
- Supplier selection: A lower-priced supplier with a long or inconsistent lead time can cost more overall than a closer, more reliable one.
Lead time variability matters as much as the average. A supplier that delivers in 10 days every time is easier to plan around than one that delivers in anywhere from 5 to 20 days.
How Lead Time Is Calculated
A basic way to calculate order lead time is:
Lead Time = Order Receipt Date − Order Placement Date
For more detailed supply-chain planning, lead time can be divided into several stages:
- Pre-processing time: Activities before an order enters the supplier’s process, such as requisition, approvals, and purchase-order processing.
- Processing time: Supplier production, picking, packing, and transportation activities.
- Post-processing time: Receiving, inspection, quality checks, and putaway before inventory becomes available.
The exact components can vary depending on the process and planning system. SAP, for example, includes activities such as planned delivery, transportation, and goods-receipt processing when calculating certain supply-chain lead times.
Types of Lead Time
Common types of lead time include:
- Supplier Lead Time: Time required by a supplier to process and deliver an order.
- Production Lead Time: Time required to manufacture a product.
- Order Lead Time: Time from receiving a customer order until it is ready for shipment.
- Transportation Lead Time: Time required to move goods between locations.
- Customer Lead Time: Total time from customer order placement to delivery.
- Cumulative Lead Time: Total end-to-end time across multiple supply-chain stages.
Example of Lead Time
An electronics assembler in Noida buys printed circuit boards from a supplier in Chennai. Its lead time for each order is built up as follows:
Stage : Time
- Purchase requisition and PO approval : 1 day
- Supplier processing and production : 6 days
- Road transit, Chennai to Noida : 4 days
- Receiving and quality inspection : 1 days
- Total lead time : 4 days
If the assembler uses 200 boards a day, it needs at least 2,400 boards available to cover usage during those 12 days, plus safety stock for any delay. Cutting transit time by switching to a faster freight mode, or approving POs the same day, reduces the stock it needs to hold.
Related Terms
- Safety Stock
- Reorder Point
- Supplier Lead Time
- Cycle Time
- Order Cycle Time
- Demand Forecasting
- Economic Order Quantity (EOQ)
- Stockout
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FAQs
Q1. What is the difference between lead time and cycle time?
Lead time is measured from the customer’s or buyer’s point of view, from the order. Cycle time measures how long it takes to complete one unit of work within a process. Cycle time is usually one part of the total lead time.
Q2. How can a company reduce lead time?
Common methods include working with suppliers located closer to the point of use, sharing demand forecasts with suppliers, shortening internal approval steps, using faster transport modes, and keeping key raw materials in stock.
Q3. Why does lead time variability matter?
Planning systems use lead time to decide when to reorder. If actual lead time swings widely, the business either runs out of stock or has to carry extra safety stock to protect against the worst case.
Q4. Is lead time only relevant to purchasing?
No. Lead time applies to procurement, manufacturing, warehousing, transportation, and customer fulfilment. Each stage has its own lead time, and together they make up the total time to serve the customer.