Reorder Point Calculator
Calculate the stock level that triggers a reorder — lead-time demand plus safety stock — so you order before stockout.
Reorder point = (average daily demand × lead time) + safety stock. When on-hand stock falls to this level, place the replenishment order — lead-time demand covers normal sales while you wait; safety stock absorbs the surprises.
Sources & references
- Standard inventory control / reorder-point models
- Lead-time demand and safety-stock interaction
Inventory formulas use the model and inputs you provide — they are decision aids, not guarantees. EOQ, safety-stock and reorder math rest on assumptions (demand pattern, lead-time stability, cost accuracy) that rarely hold perfectly; treat results as a starting point and adjust to your data, service-level target and risk tolerance.
The reorder point answers 'when do I order again?' — and getting it wrong costs both ways: too high and you carry needless stock, too low and you stock out before the replenishment arrives. The formula is intuitive: reorder point = (average daily demand × lead time) + safety stock. The first term covers what you'll sell while waiting for the order; the second absorbs the variability the average hides. This calculator computes it and shows the days of cover it represents.
About Reorder Point Calculator
The logic is a countdown. When stock drops to the reorder point, you have exactly enough — on average — to last the lead time, with safety stock as the buffer against a demand spike or a late delivery. Order at that moment and the new stock should land just as you'd otherwise have run dry. Order later and you're gambling that nothing goes wrong during the lead time; order much earlier and you're holding inventory you didn't need yet. Two inputs make or break it. Lead time must be the REAL replenishment time (order placement to shelf-available, including supplier processing and your receiving), not the supplier's optimistic quote — and if lead time varies, that variability belongs in the safety stock. Safety stock itself should come from a service-level calculation (see the safety-stock calculator), not a gut number. Get those right and the reorder point becomes the trigger that quietly prevents stockouts; guess them and it's just a number that fires too early or too late. Pair with EOQ (how much to order) for a complete reorder policy.
How to use Reorder Point Calculator
- 1Set each input — average daily demand (units), lead time (days), safety stock (units) — using your own figures.
- 2The estimate recomputes instantly as you type; no submit button, no waiting.
- 3Review the line-item breakdown to see how each component contributes to the total.
- 4Click “Copy quote” to paste the itemised result into an email, quote or audit note.
Why use Reorder Point Calculator?
- ✓Itemised line-by-line breakdown, not just a single opaque total
- ✓Copy-ready output for emails, quotes and audit notes
- ✓Recomputes live as you type — compare scenarios in seconds
- ✓Free and private — nothing you enter leaves your browser
Frequently asked questions
What is the reorder point formula?+
Reorder point = (average daily demand × lead time in days) + safety stock. The first part is lead-time demand — what you expect to sell while the replenishment order is in transit; the second is the buffer for variability. When on-hand stock falls to this level, you place the order, timed so new stock arrives just as you'd run out under normal conditions.
How is reorder point different from safety stock?+
Safety stock is a component OF the reorder point, not a substitute. Safety stock is the buffer for uncertainty (demand spikes, late deliveries); the reorder point is the actual trigger level = lead-time demand + safety stock. You calculate safety stock first (from demand/lead-time variability and your target service level), then add lead-time demand to get the reorder point. One is the cushion; the other is the alarm.
What lead time should I use?+
The full, realistic replenishment cycle: from the moment you decide to order until the stock is actually available to sell — supplier order processing, production/picking, transit, your receiving and put-away. Use your observed average, not the supplier's marketing quote. And critically, if lead time VARIES, don't just average it into the reorder point — that variability is a major driver of safety stock, where it's handled statistically rather than buried in an average.
Should the reorder point change over time?+
Yes — it's not set-and-forget. Demand shifts with seasons, trends and promotions; lead times change with supplier performance and disruptions. Review reorder points periodically (and especially before known demand peaks or after a lead-time change), recomputing from current daily demand and lead time. A reorder point set on last year's numbers is a stockout or an overstock waiting to happen. Dynamic items deserve dynamic reorder points.
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