Lead time
The time between placing an order with a supplier and having the goods ready to sell. It is the single biggest input into your reorder point.
Lead time is not what the supplier promises. It is what actually happens, measured from the day you place the order to the day the goods are on your shelf and sellable.
Count the whole chain
Order placement. The supplier's own dispatch delay. Transit. Unloading, checking and putting away. A supplier who dispatches in two days but whose consignment takes six days on the road has an eight-day lead time, plus whatever it takes you to receive it.
Measure it, do not assume it
Every purchase order gives you a data point: the date you raised it and the date you received against it. After a dozen orders you know the real average and, more usefully, the worst case. That worst case is what your safety stock is sized against.
It moves
Festival season, monsoon, a supplier changing their transporter, a plant shutdown. Lead time is not a constant you set once. Revisit it for your main suppliers a few times a year, and any time a delivery is badly late.
How KillStock handles it
Purchase orders and their receipts are recorded together, so the gap between raising an order and receiving it sits in your records rather than in someone's memory, and supplier performance is one of the standard reports.
A common mistake
Using the supplier's quoted lead time in your reorder point. Quotes are optimistic; your own history is not.