Lead time is the total time from a customer’s order (or your purchase order) until the goods are delivered. It includes waiting, production and shipping. Knowing it helps set reorder points – the stock level at which to reorder so you don’t run out.
How to use the Lead Time Calculator
- Lead time type
- Pre-processing time
- Processing time
- Post-processing / shipping time
- Supply delay
- Reorder delay
- Order date
- Count
- Daily usage (for reorder point)
Results update as you type, and every field accepts the units shown in its menu.
How it works
Choose the type of lead time, enter its parts in days, and the order date and whether to count working days only.
Tips
- Track a typical week before planning – real figures beat estimates.
- Break big tasks into smaller pieces and plan buffer time for interruptions.
- Re-run the numbers when your inputs change so plans stay realistic.
- Use results as a guide for decisions, not as a precise prediction.
Common mistakes to avoid
- Counting calendar days when the deadline is in working days (or the reverse).
- Forgetting breaks, setup and handover time.
- Assuming every day is as productive as your best day.
Inputs explained
| Field | What to enter |
|---|---|
| Lead time type | Choose one: Manufacturing, Supply chain |
| Pre-processing time | In days |
| Processing time | In days |
| Post-processing / shipping time | In days |
| Supply delay | In days |
| Reorder delay | In days |
| Order date | A date |
| Count | Choose one: Calendar days, Working days (Mon–Fri) |
| Daily usage (for reorder point) | A number |
Example values
How the main result changes when Pre-processing time changes and everything else stays at the example values above:
| Pre-processing time (days) | Lead time (days) |
|---|---|
| 1 | 9 |
| 1.5 | 9.5 |
| 2 | 10 |
| 2.5 | 10.5 |
| 3 | 11 |
| 4 | 12 |
Formula
Manufacturing lead time = pre-processing + processing + post-processingSupply chain lead time = supply delay + reorder delayDelivery date = order date + lead time (calendar or working days)Worked example
Inputs — Lead time type: Manufacturing; Pre-processing time: 2 days; Processing time: 5 days; Post-processing / shipping time: 3 days; Supply delay: 7 days; Reorder delay: 3 days; Order date: 2026-10-25; Count: Calendar days; Daily usage (for reorder point): 20.
Results — Lead time = 10 days; Expected delivery date = Wed, November 4, 2026; Reorder point (lead time × daily usage) = 200.
Frequently asked questions
What is the difference between lead time and cycle time?
Lead time runs from order to delivery; cycle time is only the time spent actively working on a unit.
How do I calculate a reorder point?
Lead time × average daily usage, plus safety stock for variability.
How can I shorten lead time?
Reduce waiting between steps, keep key materials in stock and choose closer suppliers.
What formula does the Lead Time Calculator use?
Manufacturing lead time = pre-processing + processing + post-processing.