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Reorder Point Calculator: When to Reorder Stock

Enter your average daily usage, supplier lead time and safety stock to get the exact inventory level that should trigger your next purchase order.

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Reorder point
1,330 units
Usage during lead time
1,080 units

Built by Rankite, the SEO team behind Swordfish AI's +400% revenue and Zluri's +45% organic growth. See the case studies

Reorder point is the inventory number that tells you exactly when to place a new purchase order, not by gut feel but by the math of how fast you sell and how long a replacement takes to arrive. Get it wrong and you either stock out and lose sales, or you order too early and tie up cash in inventory sitting on a shelf. This calculator takes your daily usage, lead time and safety stock and returns the exact trigger point.

How to calculate reorder point

Multiply average daily usage by lead time in days, then add safety stock. If you sell 120 units a day, your supplier takes 9 days to deliver a new order, and you hold 250 units of safety stock, the math is 120 times 9, which is 1,080 units used during the wait, plus 250 units of buffer, for a reorder point of 1,330 units. Once your on hand inventory drops to that level, it is time to order, not before and not after.

Why safety stock is part of the formula

Safety stock exists because neither your sales pace nor your supplier's delivery time is perfectly predictable. A supplier running a few days late, a sudden spike in demand, or a shipping delay can all eat into the buffer you would otherwise have. Without safety stock built into the formula, the reorder point only covers the average case, and any deviation from average turns into a stockout. Adding it shifts the trigger point earlier by exactly enough to absorb reasonable surprises.

Why lead time cannot be skipped

Reordering based purely on how fast you sell, without factoring in how long a new order takes to arrive, is one of the most common inventory mistakes. A product that sells fast but has a long lead time needs to be reordered much earlier than the daily sales number alone would suggest, since a large amount of stock will move during the wait. Lead time is what converts a simple sales rate into an actual, usable trigger point for action.

A well tuned reorder point keeps products in stock for the customers organic and AI search are already sending you. Request a free SEO audit and we will show you where more of that demand is available to capture.

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FAQ

Reorder Point Calculator: questions, answered

What is a reorder point?
The reorder point is the inventory level at which you need to place a new purchase order so stock does not run out before the replacement arrives. Once your remaining stock drops to this number, it is time to reorder, not sooner and not later.
How do you calculate reorder point?
Multiply average daily usage by lead time in days, then add your safety stock. If you sell 120 units a day, your supplier takes 9 days to deliver, and you keep 250 units of safety stock, the reorder point is 120 times 9, plus 250, which is 1,330 units.
What is safety stock and why is it added?
Safety stock is extra inventory held on top of expected demand to absorb the unexpected, a supplier running late, a sudden sales spike, or a shipment delay. Adding it to the reorder point formula means you place the order early enough to cover both normal usage during lead time and a reasonable buffer for surprises.
What happens if I ignore lead time?
If you reorder based only on how much you sell without accounting for how long the new stock takes to arrive, you will place orders too late and run out before the replacement shows up. Lead time is what turns a simple usage number into an actual trigger point for action.
Should the reorder point change over time?
Yes. Average daily usage shifts with seasonality and demand trends, and lead times can change as suppliers get busier or shipping conditions change. Recalculate the reorder point whenever either input moves meaningfully, rather than setting it once and leaving it fixed indefinitely.

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