Lead time is the wait between a request coming in and the requester receiving the result. For an online store, that wait runs from the moment a customer places an order to the moment the parcel reaches their door.
That wait often holds more idle time than work. According to Daniel Vacanti, author of Actionable Agile Metrics for Predictability, the average flow efficiency of teams that are new to Lean or pay little attention to their flow is between 5% and 15%.
Put differently, at those teams an item sits blocked or stuck in a queue for 85% to 95% of its total duration. This article on lead time covers its stages, types, calculation, differences from cycle time, and ways to shorten it.
What Is Lead Time?
In practice, lead time covers all the time a requester experiences, including time spent in a queue and waiting for approval, on top of the work itself. For that reason, the number is almost always larger than the working time alone.
Lead time is not limited to goods: software teams count it from the moment a feature request is logged until the feature is released. Its counterpart in customer service is resolution time, which runs from ticket creation until the issue is marked as resolved.
Units follow the process: hours for a helpdesk ticket and days for a parcel delivery. When comparing two lead times, make sure both use the same day count, either calendar days or working days.
The Stages That Make Up Lead Time
Lead time is built from six sequential stages, and only one of them involves working on the order itself. The names and order differ from business to business, but the waiting pattern is similar.
- Order processing: The order is recorded and verified, then waits for internal approval before work begins.
- Queue: The order waits its turn because the machines or the team are still busy with other orders.
- Setup: The team reconfigures the machines and opens system access before the work starts.
- Production: The team turns materials into the product or service that was ordered, and only this stage adds direct value for the customer.
- Inspection: The team checks the result and sends defective items back for repair.
- Delivery: The goods are packed and shipped until they reach the customer.
The other five stages are waiting or supporting time, so efforts to shorten lead time usually start with them. Speeding up production itself comes second.
Types of Lead Time
Lead time comes in five types, defined by where the count starts and where it ends: customer, supplier, production, delivery, and cumulative. Two teams that use different starting points will produce numbers that cannot be compared.
| Type | Counted From | Counted Until | Wooden Cabinet Workshop Example |
|---|---|---|---|
| Customer lead time | Order received | Cabinet received by the customer | 13 days |
| Supplier lead time | Wood ordered from the supplier | Wood received at the warehouse | 10 days |
| Production lead time | Work order issued | Cabinet finished and inspected | 9 days |
| Delivery lead time | Cabinet leaves the warehouse | Cabinet received by the customer | 3 days |
| Cumulative lead time | Order received, with no wood in stock | Cabinet received by the customer | 23 days (13 + 10) |
In this example, the customer waits 13 days if the wood is already in the warehouse and 23 days if it must be ordered first. The 10-day difference is the supplier lead time.
How to Calculate Lead Time
Lead time is calculated in two ways: adding up the duration of each stage, or dividing the number of jobs in progress by the number of jobs completed per day. The first method suits a single order, while the second produces an average across all orders.
Adding Up the Duration of Each Stage
The first method adds the duration of every stage that one order passes through, from receipt to delivery. The formula is lead time = order processing + queue + setup + production + inspection + delivery.
The wooden cabinet workshop recorded the duration of each stage for one order, with the wood already in the warehouse.
| Stage | Duration |
|---|---|
| Order processing | 1 day |
| Queue | 3 days |
| Setup | 1 day |
| Production | 4 days |
| Inspection | 1 day |
| Delivery | 3 days |
| Lead time | 13 days |
Production takes only 4 of the 13 days, while the other 9 days go to order processing, queue, setup, inspection, and delivery. That share of active work is called flow efficiency, and it comes to about 31% in this example.
Calculating the Average with Little’s Law
The second method uses Little’s Law, a queuing result proven by John Little in 1961. The formula is average lead time = orders in progress ÷ orders completed per day.
An online store holds 60 unshipped orders and ships 12 orders per day, so the average order waits 60 ÷ 12 = 5 days before it leaves. If the number of orders processed at the same time is capped at 36 and the shipping rate stays the same, that average drops to 3 days.
This result describes a long-run average across all orders, so it cannot predict how long one specific order will take. It holds only while the number of incoming and completed orders stays roughly in balance.
Lead Time, Cycle Time, and Takt Time: What Is the Difference?
Lead time measures the full time a request spends in the system, from arrival to delivery. Cycle time covers only the time from the start of work on an item to its completion, while takt time is the production pace needed to match customer demand.
| Term | Question It Answers | How It Is Measured |
|---|---|---|
| Lead time | How long does the customer wait from ordering to receiving? | From the request arriving to the result being received |
| Cycle time | How long is one item worked on once it starts? | From the start of work to completion |
| Takt time | How fast must production move to match demand? | Available production time ÷ customer demand |
| Delivery time | How long are the goods in transit? | From leaving the warehouse to being received |
At a restaurant, lead time is the wait from the guest ordering to the dish reaching the table, while cycle time is how long the chef spends cooking it. Takt time answers a different question: a kitchen that is open for 600 minutes and receives 150 orders must finish one order every 4 minutes.
Why Does Lead Time Matter for a Business?
Lead time determines when stock must be reordered and which delivery date can be promised to a customer. Those two decisions involve the purchasing, warehouse, production, and sales teams at the same time.
- Reorder point: Stock is reordered when inventory falls to the level that covers usage during the lead time plus safety stock.
- Customer promises: Measured lead time lets the deadlines in a service level agreement (SLA) be set from data.
- Working capital: Goods waiting in queues and warehouses tie up cash, and at the same production speed, a shorter lead time means less work in progress.
- Supplier evaluation: Each supplier’s lead time history shows who is consistent and who often misses.
The reorder point formula is (daily usage × lead time) + safety stock. With usage of 40 units per day and a lead time of 7 days, demand while waiting for the supplier reaches 280 units.
After adding 80 units of safety stock, the order is placed when 360 units remain. If the lead time stretches to 10 days, that number rises to 480 units.
The spread of lead times matters as much as the average. A supplier that sometimes delivers in 3 days and sometimes in 14 requires more safety stock than one that always delivers in 7.
How to Shorten Lead Time
Shortening lead time starts with cutting the waiting, because that is where most of the time is lost. The six steps below can be carried out in order.
- Map the flow. Draw every step from order received to order delivered with value stream mapping, then record the duration of each step.
- Limit work in progress. Fewer open orders mean shorter queues, as the Little’s Law calculation above shows.
- Review approvals that are almost always granted. Replace them with automatic rules for low-risk transactions, and keep human approval for decisions that truly need weighing.
- Prepare a backup supplier. A second supplier, especially one located closer, keeps production running when the main supplier is late.
- Automate repetitive steps. Order recording, status notifications, invoicing, and access for new staff can run through workflow automation without waiting for a busy person.
- Measure and review every month. Compare actual lead time with the promise made to customers, then trace which stage most often misses.
A shorter lead time is not always a better one. Cutting inspection or safety stock too far can raise the defect count and the risk of stockouts, so aim for a consistent lead time before a short one.
Conclusion
Lead time is an honest measure of how long a request takes, because it counts the waits that never appear in a production report. Once it is broken down by stage, the actual work often takes only a small share of the total time, such as 4 of the 13 days in the cabinet workshop example.
Shortening lead time means cutting the waiting at every stage, from production queues to approvals, without loosening quality controls. The same principle applies beyond factories and warehouses, including personal data compliance, where requests from data subjects need prompt answers and breach incidents need quick handling.
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FAQ
Lead time is counted from the moment a request comes in and includes waiting time, while cycle time is counted only from the moment work on the item starts.
There is no fixed number, because the benchmark is the promise made to customers and the capability of suppliers. A lead time is considered good when it is consistent and matches what was promised.
No. Delivery time is only one stage within lead time, covering the goods’ trip until the customer receives them.
Divide the number of orders in progress by the number of orders completed per day (Little’s Law). Another way is to average the lead time of every order completed in a given period.
Not always. A lead time forced too short can lower quality or drain safety stock, so consistency should come first.
