Lead time is two numbers, and everybody quotes one

Ask a supplier how long something takes and you will usually get one number. Ask what is inside it and you will find two, and they behave nothing like each other.

Production days

This is queue time plus run time. It stretches when the factory is busy, and it is largely insensitive to money. Paying more rarely buys a place further up the queue - the line is committed to the orders already on it. Ordering earlier always does.

Production days are also the half that moves without warning. A factory that quoted twelve days in a quiet month quotes twenty-five in the run-up to a season, and the reason has nothing to do with you.

Shipping days

This is a transport decision, and it is extremely sensitive to money. Air freight collapses it and can destroy the unit economics of a cheap, bulky component. Sea freight is the opposite: it makes the arithmetic work and gives you weeks of exposure to weather, ports and paperwork.

The right answer changes per order, and sometimes per line within an order. That is precisely why it should stay a separate number instead of being folded into one figure you cannot take apart when the situation changes.

What a blended number hides

Consider two suppliers, both quoting thirty days.

• One is twenty-five days of production and five days of trucking.
• The other is ten days of production and twenty on a boat.

These are not the same promise. The second one has three weeks of transit exposure the first does not, and if it slips you find out late, when the container is already at sea and there is nothing to do about it. The first slips early, at the factory, where you can still react.

You cannot see any of that in "thirty days". The difference only becomes visible when the numbers are apart.

What this looks like here

Every offer in our catalog carries its own lead time and its own shipping days, and the product page adds them for you rather than instead of you - so you are comparing arrival dates, with the makeup of each still on screen. Volume breaks can carry their own shipping days too, because a bigger run often moves differently from a small one.

Then the forecasting side works backwards from the sum. The stockout date is your runway at the rate you actually consume the item; subtract lead time, subtract shipping, subtract the safety days you set, and you have the last day an order can be placed and still arrive before the shelf is empty. That date is the one worth acting on. The stockout date is just what it is derived from.

And where it ships from

One more reason to keep the numbers separate: the warehouse. A product flagged Shipped from USA ships to you from a domestic warehouse - sometimes at the offer itself, sometimes only at one of its volume breaks. That flag is a statement about where the goods leave from, not a claim about where they were manufactured. Stock on a US shelf turns the shipping half into days instead of weeks; the overseas run keeps the factory price and takes the boat. Which trade you want depends on the week you are in rather than on a policy, and keeping both numbers visible is what lets you choose.