Lead Time Calculator › How to calculate lead time
Guide
Lead time is calculated by subtracting the order date from the delivery date: Lead Time = Delivery Date − Order Date. If an order placed on March 1 arrives on March 15, the lead time is 14 days. This guide covers the formula, average lead time, business-day rules, and worked examples — or you can skip straight to the calculator.
There are three versions of the same relationship, depending on which value you already know:
Lead Time = Delivery Date − Order Date
Use this to measure how long past orders actually took. It is the basis for supplier scorecards and average lead time.
Delivery Date = Start Date + Lead Time
Use this when you know when you will order and the supplier’s quoted lead time, and you want to know when it arrives.
Order-By Date = Need-By Date − Lead Time
Use this when you have a deadline and need the latest safe date to place the order. This is the version most planners use daily.
The ASCM (formerly APICS) Supply Chain Dictionary defines lead time as the span between the recognition of a need and its fulfillment. In practice, total lead time is the sum of stages:
Total Lead Time = Order Processing + Production + Shipping + Receiving
Don’t confuse lead time with cycle time: cycle time counts only active work, while lead time counts all elapsed time, including waiting. In process analysis the two are linked by Little’s Law (Little, 1961): average lead time = work-in-process ÷ throughput.
Average Lead Time = Sum of Lead Times ÷ Number of Orders
| Order | Ordered | Delivered | Lead time |
|---|---|---|---|
| A | Jun 1 | Jun 11 | 10 days |
| B | Jun 3 | Jun 21 | 18 days |
| C | Jun 10 | Jun 24 | 14 days |
Average lead time = (10 + 18 + 14) ÷ 3 = 14 days. Many teams also track the longest recent lead time, because planning against the average alone means roughly half of orders arrive late.
A “10-day lead time” can mean two different dates. Calendar days count every day of the week; business days exclude Saturdays and Sundays (and sometimes holidays). Over longer lead times the gap is large: a 12-week lead time is 84 calendar days, but 60 business days spans roughly 16½ calendar weeks.
Rules of thumb: freight carriers and customs usually quote calendar or transit days, manufacturers and service teams usually quote business days — but always confirm. If holidays matter in your supply chain, add them on top of the weekend exclusion.
Ordered: May 5. Delivered: June 2. Lead time: 28 calendar days (4 weeks).
Order date: today. Quoted lead time: 6 weeks. Delivery: 42 calendar days from today. See the exact date →
Need by: December 1. Lead time: 8 weeks. Order by: October 6 (December 1 minus 56 days). Add a safety buffer of a few days if the deadline is firm.
Start: a Monday. Lead time: 10 business days. Delivery: the Monday two weeks later — 14 calendar days elapse even though only 10 are counted.
Real-world lead times, record builds, and famous waits — every fact sourced.
Apple announced the original iPhone on January 9, 2007, but it didn't go on sale until June 29, 2007 — a 171-day wait between reveal and delivery.
Steve Jobs unveiled it at Macworld with no finished product ready to ship, giving Apple under six months to finalize it. Source: Wikipedia
Tesla unveiled the Cybertruck on November 21, 2019, but the first customer deliveries didn't happen until November 30, 2023 — a lead time of just over four years.
Production slipped roughly two years past Tesla's original late-2021 target before the Austin delivery event. Source: NPR
The James Webb Space Telescope launched on December 25, 2021 — about 25 years after initial designs began in 1996.
Early plans targeted a 2007 launch, but redesigns, cost growth, and testing pushed it back nearly 15 years. Source: Wikipedia
During the global chip shortage, average semiconductor lead times hit a record 27.1 weeks in May 2022 — over six months of waiting.
Lead times had already hit then-record highs of 18 weeks in June 2021 and kept climbing for nearly a year, per Susquehanna Financial Group's tracking. Source: KED Global
US power transformer lead times ballooned from about 50 weeks in 2021 to an average of 120 weeks by 2024 — with large units taking 80 to 210 weeks.
Some grid transformers ordered today arrive roughly four years later, per Wood Mackenzie's 2024 analysis. Source: Wood Mackenzie
Fabricating a single semiconductor chip takes about 12 weeks — and up to 14–20 weeks for advanced processes — before roughly 6 more weeks of assembly, test, and packaging.
The Semiconductor Industry Association puts total order-to-delivery lead time at up to 26 weeks even in normal conditions. Source: Semiconductor Industry Association
After Pan Am ordered 25 Boeing 747s in April 1966, Boeing had just 28 months to design the jumbo jet — rolling it out on September 30, 1968.
That was about two-thirds the normal development time, and the breakneck-pace team earned the nickname 'The Incredibles.' Source: Wikipedia
The Empire State Building was built in just 410 days: the first steel column was set on March 17, 1930, and the skyscraper officially opened on May 1, 1931.
Crews erected the 102-story tower's steel frame at a pace of up to four and a half stories per week. Source: History.com
In November 1942, the WWII Liberty ship SS Robert E. Peary was assembled in a record 4 days and 15.5 hours, from keel laying to launch.
Guinness World Records credits extensive prefabrication for the fastest-ever ship build — part of a wartime race to outbuild U-boat sinkings. Source: Guinness World Records
When the container ship Ever Given wedged across the Suez Canal in March 2021, it blocked the waterway for six days — holding up an estimated $9.6 billion of trade per day.
Lloyd's List estimated roughly $400 million of goods delayed per hour while the ship was stuck. Source: gCaptain
Shipping a full ocean container from Shanghai to Los Angeles typically takes about 27 to 36 days in transit.
Smaller less-than-container-load shipments on the same route run even longer, at roughly 29 to 41 days, per freight marketplace Freightos. Source: Freightos
Airbus and Boeing had a combined backlog of 16,683 unfilled aircraft orders as of April 2026 — roughly 12 years of work at current production rates.
Order a new jet today and, on average, you're queuing behind more than a decade of earlier customers. Source: Aerospace Global News
The Hermès Birkin bag was once reputed to have a waiting list of up to six years — and even today a first-time customer can't simply walk in and buy one.
Hermès scrapped the formal waitlist in 2010; buyers typically must first build a purchase history of other goods. Source: Wikipedia
US retailers often begin planning for the winter holidays in January and typically finalize the bulk of their Christmas orders by the end of June — about six months ahead.
Ocean-shipped holiday goods start arriving at US warehouses by mid-summer, which is why ports peak months before December. Source: Fortune / AP
Boeing's 787 Dreamliner was due to reach its launch customer in 2008, but the first delivery didn't happen until September 25, 2011 — about three years late.
Supply chain problems, fastener shortages, and software issues repeatedly pushed back the carbon-composite jet's debut. Source: Wikipedia
What is the formula for lead time?
Lead Time = Delivery Date − Order Date. For planning forward, Delivery Date = Start Date + Lead Time. For planning backward, Order-By Date = Need-By Date − Lead Time.
How do you calculate average lead time?
Average Lead Time = Sum of individual lead times ÷ Number of orders. Measure every order in the same unit (calendar or business days), add them up, and divide by the order count.
Is lead time counted in calendar days or business days?
Either — but be consistent, and always confirm which convention a supplier’s quote uses. Calendar days count every day; business days count only weekdays.
What is the difference between lead time and cycle time?
Lead time is total elapsed time from request to fulfillment, including waiting. Cycle time is only the time spent actively working on the item, so lead time is always equal to or longer than cycle time.