Free Lead Time Calculator for Reorder Planning
Calculate total lead time, reorder point, safety stock, and the latest date to place your next purchase order. Model production, freight, customs, demand, and inventory in one free planning tool.
The calculator opens with a realistic ocean-import example. Replace the defaults with one SKU's actual numbers to see when its reorder window closes.
Total replenishment lead time
56 days
Reorder point
1,400
Safety stock
280 units
Days of cover
75 days
Order by
Calculating date
Calculate Lead Time and Reorder Point
Results update instantly as you replace the example values.
A reorder date only helps if someone watches it.
SupplyAutomate keeps stock, supplier lead times, and purchase orders together, then flags the SKUs whose reorder windows are closing.
Replenishment Results
Lead time and reorder analysis
Total Lead Time
56 days
Production + transit + customs
Reorder Point
1,400
Covers a 70-day horizon with the buffer
Healthy stock
Stock is healthy. You have about 5 days before the order needs to be placed.
Safety Stock
280 units
Days Until Stockout
75 days
Latest Order Date
Calculating date
5 days from now
Coverage At Reorder
10 weeks
Go beyond a one-off calculation
A reorder date is only useful if something watches it
SupplyAutomate tracks stock, suppliers, and purchase orders together, so the reorder point you just calculated becomes an alert your team acts on instead of a number in a spreadsheet nobody reopens.
How Lead Time Calculation Works
Reorder timing improves when every stage between PO placement and warehouse receipt is modeled explicitly. Once the order date is clear, turn the plan into a supplier-ready purchase order.
1. Supplier and production time
Start with how long your supplier needs to produce and prepare the goods before they can ship. This is the first term in any lead time calculation.
2. Transit and customs time
Add ocean or air transit, customs clearance, and the handoff into your warehouse. These are the days most reorder plans forget.
3. Safety buffer discipline
The buffer absorbs late shipments and demand spikes. It sits on top of lead time rather than inside it, so you can see what each one costs you.
The Formulas This Calculator Uses
Nothing here is hidden. These are the exact calculations behind every number above.
Total lead time
production + transit + customs
The safety buffer is deliberately excluded. Lead time is what your supply chain takes; the buffer is a cushion you choose.
Reorder point
(daily demand × lead time) + safety stock
The standard reorder point formula: cover demand across the lead time, then hold the buffer on top. Use the MOQ calculator to compare that timing with the quantity your supplier requires.
Safety stock
daily demand × safety buffer days
A days-of-cover model. It is simpler than a service-level formula and does not need demand variability data you probably do not have yet.
Latest order date
today + (days of cover − lead time − buffer)
If that date has already passed, the page says how many days late you are. Pair it with the sea vs air freight calculator when you need to buy those days back.
Why Lead Time Planning Matters
Avoid preventable stockouts
Reorder points only work when lead time and buffer assumptions are grounded in reality.
Order with better timing
Knowing the latest safe order date makes replenishment decisions easier across sourcing, freight, and inventory teams.
Set realistic safety stock
A structured lead-time model helps you carry the right buffer instead of guessing based on recent pain.
Reorder alerts
Surface timing risk earlier
Planning rhythm
See order deadlines clearly
Operational accuracy
Track the difference between planned and real lead time
Lead Time Calculator FAQ
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The calculator is free. Missing the date is not.
Stockouts are not a math problem. They are a memory problem.
You just worked out exactly when to reorder. The hard part is remembering on that day, for every SKU, while suppliers slip and demand moves. SupplyAutomate keeps stock levels, supplier lead times, and purchase orders in one workspace and tells you when the window is closing.
SupplyAutomate
Example replenishment view
SKU CB-1180 · 56-day lead time
5 days
Until the order must be placed
56 days
Actual supplier lead time
280
Safety stock held
Aug 11
Latest safe order date
Alerts fire before the window closes, not after the stockout.