# What is my lead time?

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.

- Page: https://www.acalculator.org/logistics/lead-time-calculator
- JSON spec: https://www.acalculator.org/logistics/lead-time-calculator.json
- Version: ca7a8c2b9e9a

## Default answer

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.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| date | Order date | The day the order is placed. |
| proc | Order processing | Days for the supplier to accept and prepare the order. |
| prod | Production or picking | Days to make the goods or pick them from stock. |
| ship | Transit | Days the shipment is on the way. |
| recv | Receiving | Days to unload, check and put the goods into stock. |
| days | Count | Whether the days are calendar days, or business days that skip Saturdays and Sundays. |
| demand | Daily demand (optional) | Average units used or sold per day, counted in the same kind of days, for the reorder point. |
| safety | Safety stock (optional) | Units kept in reserve against late deliveries or extra demand. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| days | Lead time | Order processing + production + transit + receiving, in days. |
| arrival | Goods in stock on | The order date plus the lead time, in calendar days or business days. |
| calendarDays | Calendar days | The calendar days from the order date to the date the goods are in stock. |
| weeks | Lead time in weeks | The calendar days ÷ 7. |
| reorderPoint | Reorder point | Daily demand × lead time + safety stock: order again when stock falls to this level. |

## 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.

## Assumptions

- 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

1. date = 2026-10-05, proc = 2, prod = 10, ship = 5, recv = 1, days = calendar gives days = 18, arrival = 2026-10-23, calendarDays = 18. Source: Wikipedia, Lead time (supply chain: from the order to the goods ready), https://en.wikipedia.org/wiki/Lead_time.
2. date = 2026-10-05, proc = 2, prod = 10, ship = 5, recv = 1, days = business gives days = 18, arrival = 2026-10-29, calendarDays = 24. Source: Wikipedia, Lead time (supply chain: from the order to the goods ready), https://en.wikipedia.org/wiki/Lead_time.
3. date = 2026-10-09, proc = 1, prod = 0, ship = 3, recv = 0, days = business, demand = 40, safety = 100 gives days = 4, arrival = 2026-10-15, reorderPoint = 260. Source: Wikipedia, Reorder point (reorder point = normal consumption during lead time + safety stock), https://en.wikipedia.org/wiki/Reorder_point.
4. date = 2024-02-27, proc = 0, prod = 0, ship = 3, recv = 0, days = calendar, demand = 12.5 gives arrival = 2024-03-01, reorderPoint = 37.5. Source: Wikipedia, Reorder point (reorder point = normal consumption during lead time + safety stock), https://en.wikipedia.org/wiki/Reorder_point.

## FAQ

### 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.

## Sources

- Wikipedia, Lead time: in a supply chain, the time from the moment the customer places an order to the moment it is ready for delivery. https://en.wikipedia.org/wiki/Lead_time (retrieved 2026-10-02)
- Wikipedia, Reorder point: reorder point = normal consumption during lead time + safety stock. https://en.wikipedia.org/wiki/Reorder_point (retrieved 2026-10-02)