What is my lead time?
Type the order date and the days each step takes. The lead time calculator adds them up, finds the day the goods are in stock, and, with your daily demand, tells you when to reorder.
- Lead time
- 18
The lead time is 18 days, so goods ordered on October 2, 2026 are in stock on Tuesday, October 20, 2026.
- Goods in stock on
- Tuesday, October 20, 2026
- Calendar days
- 18
- Lead time in weeks
- 2.6
Answer for the example date Friday, October 2, 2026. It changes to today's date when the page loads.
Lead time: 18. The lead time is 18 days, so goods ordered on October 2, 2026 are in stock on Tuesday, October 20, 2026.
How to calculate
Adds up order processing, production, transit and receiving days into the total lead time, finds the date the goods arrive (in calendar or business days), and gives the reorder point from daily demand and safety stock.
Example with the default inputs (Order date October 2, 2026, Order processing 2, Production or picking 10, Transit 5, Receiving 1, Count Calendar days) on the example date Friday, October 2, 2026: The lead time is 18 days, so goods ordered on October 2, 2026 are in stock on Tuesday, October 20, 2026.
Method: Lead time = order processing + production + transit + receiving (days); arrival = order date + lead time (calendar days, or business days skipping Saturdays and Sundays); reorder point = daily demand × lead time + safety stock.
- Business days skip Saturdays and Sundays only; public holidays are not skipped.
- Each part of the lead time is a whole number of days. Use averages from past orders, or the supplier’s quote.
- The reorder point assumes steady daily demand; the safety stock covers the variation.
Worked examples
Each example is checked against the calculator on every build.
- Order date 2026-10-05, Order processing 2, Production or picking 10, Transit 5, Receiving 1, Count Calendar days gives Lead time 18, Goods in stock on 2026-10-23, Calendar days 18.Source: Wikipedia, Lead time (supply chain: from the order to the goods ready), https://en.wikipedia.org/wiki/Lead_time
- Order date 2026-10-05, Order processing 2, Production or picking 10, Transit 5, Receiving 1, Count Business days gives Lead time 18, Goods in stock on 2026-10-29, Calendar days 24.Source: Wikipedia, Lead time (supply chain: from the order to the goods ready), https://en.wikipedia.org/wiki/Lead_time
- Order date 2026-10-09, Order processing 1, Production or picking 0, Transit 3, Receiving 0, Count Business days, Daily demand (optional) 40, Safety stock (optional) 100 gives Lead time 4, Goods in stock on 2026-10-15, Reorder point 260.Source: Wikipedia, Reorder point (reorder point = normal consumption during lead time + safety stock), https://en.wikipedia.org/wiki/Reorder_point
- Order date 2024-02-27, Order processing 0, Production or picking 0, Transit 3, Receiving 0, Count Calendar days, Daily demand (optional) 12.5 gives Goods in stock on 2024-03-01, Reorder point 37.5.Source: Wikipedia, Reorder point (reorder point = normal consumption during lead time + safety stock), https://en.wikipedia.org/wiki/Reorder_point
How it works
- Lead time L = order processing + production or picking + transit + receiving, each a whole number of days.
- Arrival date.
- Calendar days: the order date plus L days.
- Business days: start at the order date and step forward one day at a time; each Monday to Friday counts one, Saturdays and Sundays count none, until L days are counted. The order date itself is never counted, so with L = 0 the arrival is the order date.
- Calendar days = the days from the order date to the arrival date (equal to L when counting calendar days).
- Weeks = calendar days ÷ 7.
- Reorder point (when daily demand is typed) = daily demand × L + safety stock (0 when left empty). Demand counts the same kind of days as the lead time.
Rules. Each step is a whole number from 0 to 365 days. The order date is from 1900-01-01 to 2200-12-31. Daily demand is from 0 to 1,000,000,000; safety stock from 0 to 10¹².
Exact arithmetic. Demand and safety stock are read as the exact decimals you typed, so the reorder point is exact.
Output format. Days are whole numbers, weeks show 1 decimal and the reorder point 2 decimals, rounded half up; the arrival is a long date such as October 23, 2026.
Assumptions
- Business days skip weekends only, not public holidays.
- Demand is steady from day to day; safety stock covers the variation.
Worked examples by hand
Ordered Monday, October 5, 2026; 2 + 10 + 5 + 1 days, calendar days. L = 18 days. October 5 + 18 = October 23, 2026.
The same order in business days. Counting weekdays from October 6: week 1 (Oct 6 to 9) 4, week 2 (Oct 12 to 16) 9, week 3 (Oct 19 to 23) 14, then Oct 26, 27, 28, 29 make 18. Arrival Thursday, October 29, 2026, 24 calendar days after the order.
Ordered Friday, October 9, 2026; 1 + 0 + 3 + 0 business days; 40 units a day; 100 units of safety stock. L = 4. Monday 12, Tuesday 13, Wednesday 14, Thursday 15: arrival October 15, 2026. Reorder point 40 × 4 + 100 = 260 units.
Ordered February 27, 2024; 3 calendar days; 12.5 units a day. 2024 is a leap year, so the days are February 28, February 29 and March 1, 2024. Reorder point 12.5 × 3 + 0 = 37.5.
Other questions people ask
What is lead time?
The time from placing an order to having the goods ready to use or sell. It is the sum of its steps: the supplier processing the order, making or picking the goods, shipping them, and your receiving and checking them.
How do I calculate lead time?
Add the days of each step. 2 days of order processing, 10 days of production, 5 days in transit and 1 day of receiving make a lead time of 2 + 10 + 5 + 1 = 18 days.
What is the difference between calendar days and business days?
Calendar days count every day. Business days skip Saturdays and Sundays, so 18 business days from Monday, October 5, 2026 end on Thursday, October 29, 24 calendar days later.
What is a reorder point?
The stock level at which to order again so the new goods arrive before you run out: daily demand × lead time + safety stock. At 40 units a day, a 4-day lead time and 100 units of safety stock, reorder when stock falls to 40 × 4 + 100 = 260.
How much safety stock do I need?
Enough to cover a late delivery or a busy spell. Many teams start with a few days of demand and adjust from experience; statistical methods use the spread of past demand and lead times.
Does the page skip public holidays?
No. Business days skip only Saturdays and Sundays, because holidays differ by country and company. Add holiday days to the transit or processing step if they fall inside the lead time.