Lead Time

Amazon & D2C glossary · Harpy Media

Lead time is the total elapsed time from placing a purchase order to having inventory checked in, sellable, and live on the marketplace. Not the factory’s production estimate — the whole journey: manufacture, transit, customs clearance, and Amazon receiving.

What is Lead Time?

Lead time is the total elapsed time from placing a purchase order to having inventory checked in, sellable, and live on the marketplace. Not the factory’s production estimate — the whole journey: manufacture, transit, customs clearance, and Amazon receiving.

It is the single number that decides when you reorder. Everything upstream of stockouts is a lead-time calculation: too short an estimate and the listing runs dry; too long and you tie capital up in ships and warehouses weeks before the goods can earn. Getting it honest, end to end, is most of inventory management.

Why lead time dictates cash flow

Order too late and the product goes dark — revenue stops, ranking decays, and recovery costs advertising. Order too early and cash sits in transit stock that cannot be sold yet — liquidity drains months before the return arrives. Both errors are the same error: a lead time that does not match reality.

The correct model is conservative by design. Use the timeline you actually experienced last time (or the slowest plausible case), not the fastest one seen in a good month. Then reorder against that number. Sellers who build in the favourable case spend every shipment improvising around its mistakes.

The four phases, and the ones people ignore

Total lead time is the sum of four phases: manufacturing, transit, customs, and receiving. Manufacturing is the phase suppliers quote directly, and usually the only one they quote. Transit is booked, tracked, and at the mercy of ports and consolidation. Customs is variable and structural — documentation errors can add weeks on their own.

Receiving is the quiet killer. Ocean arrival is not inventory availability: the shipment must be unloaded, checked in, and reconciled at the fulfilment centre, and during peak season that queue alone can run far longer than anyone plans for. Measurement is the discipline — timestamp every phase across several shipments and use the p90: the number that covers almost every actual outcome.

In practice

A brand tracks its French press across every phase: 30 days manufacturing, 25 days ocean freight, 5 days customs, 10 days Amazon receiving — 70 days total. It places each new production order exactly 70 days before projected stockout. The new batch clears the receiving dock as the old stock depletes, and no customer ever sees an out-of-stock page.

How Harpy Media helps

Replenishment timing is part of the operating rhythm we run for brands: lead times measured phase by phase, reorder points set against the p90 rather than the average, and buffers sized to how volatile the lane really is. The aim is boring predictability — stockouts that never happen.

Lead Time FAQ

What is the difference between lead time and delivery time?

Delivery time usually means the journey itself — factory to port to dock. Lead time covers the whole operational window from placing the order to having sellable inventory on the marketplace, including production, customs, and receiving.

Why is my calculated lead time always too short?

Almost always because a phase was estimated instead of measured — usually receiving, occasionally peak-season customs. Track each phase separately across several shipments and use the slowest realistic values, not the supplier’s quote.

How much buffer should I add to lead time?

It depends on variability rather than a fixed rule of thumb: stable lanes need a little, congested or new lanes considerably more. A practical approach is to plan on the p90 of historical timings — the duration that covers nearly every shipment.