Lead Time Calculator › Working days
Working day lead times
Count only the days your suppliers actually work. Skips weekends — and public holidays, if you pick a country.
Working days from the start date
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The three terms cause more missed deadlines than any other part of lead time planning, because a supplier and a buyer can quote the same number and mean different dates.
The practical rule: 20 working days is four weeks only if no holiday falls inside the span. Across US Thanksgiving week or the UK Christmas period, the same 20 working days can stretch to five calendar weeks or more. Set the holiday region above and the calculator shows you exactly which days it removed.
Delivery date = start date + N working days, skipping Sat, Sun and any selected public holidays
A supplier quotes a 15 working day lead time and you place the order on a Monday in mid-November. Counting weekends only, you land three calendar weeks later. Add US federal holidays and Thanksgiving removes a day, pushing delivery into the following week. One holiday, one week of slip — multiplied across every open order, that is the gap between a schedule that holds and one that doesn't.
Dates are computed from the official rules each year rather than a fixed list, so the calculator stays correct for future years. Weekend-falling holidays are shifted the way the governing body shifts them.
New Year’s Day, Martin Luther King Jr. Day, Washington’s Birthday, Memorial Day, Juneteenth, Independence Day, Labor Day, Columbus Day, Veterans Day, Thanksgiving Day and Christmas Day. A federal holiday falling on a Saturday is observed the preceding Friday; one falling on a Sunday is observed the following Monday. Source: U.S. Office of Personnel Management
Note that federal holidays bind federal offices and banks. Many private manufacturers work Columbus Day and Veterans Day, and some add the Friday after Thanksgiving. Treat the result as the conservative case and confirm the shutdown calendar with your supplier.
New Year’s Day, Good Friday, Easter Monday, the early May bank holiday, the spring bank holiday, the summer bank holiday, Christmas Day and Boxing Day. When a bank holiday falls at a weekend a substitute weekday is given, normally the following Monday. Source: GOV.UK
Scotland and Northern Ireland have different bank holidays — Scotland observes 2 January and St Andrew’s Day, Northern Ireland observes St Patrick’s Day and the Battle of the Boyne. This calculator uses the England and Wales calendar.
Need calendar days, weeks, or a fixed lead time you look up often?
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
Do working days include holidays?
Not usually. A working day is a day the business is open, so weekends are always excluded and public holidays are excluded in most commercial usage — particularly in the UK, where “working day” in a contract is normally defined to exclude bank holidays. US quotes using “business days” are less consistent, so ask the supplier whether federal holidays are counted.
Is a working day the same as a business day?
In practice, yes — both mean Monday to Friday, excluding public holidays. “Business day” is the standard US term and “working day” the standard UK and European term. The difference that matters is not the word but which holiday calendar applies.
How many working days are in a week?
Five in a standard Monday-to-Friday week. So 4 weeks is 20 working days, 8 weeks is 40, and 12 weeks is 60 — before any public holidays are removed.
How do I calculate an order-by date in working days?
Count backwards from the date you need the goods, skipping weekends and holidays, for the number of working days in the lead time. Set Direction to “Backward” above and enter your need-by date as the start date.
Does the count include the start date?
No. Counting starts on the next working day after the start date, which is the standard convention for lead time quotes — an order placed Monday with a 1 working day lead time is due Tuesday.