Reorder point calculation with formula and worked example from the field. Plus 5 practical steps and a comparison table for all 3 inventory metrics.
TL;DR
Reorder point = daily consumption x lead time + safety stock. Reached: reorder immediately.
Monday morning, 7:15 AM. Your electrician is on site and needs NYM cable. The warehouse: empty. Nobody reordered. So: emergency run to the wholesaler, 45 minutes there, 45 minutes back. The electrician waits. The client waits. And you pay double: travel costs plus one hour of downtime.
According to a study by OneQrew, 42 percent of trade businesses say that monitoring delivery dates alone eats up significant time. The real cause: nobody knows when to reorder. The solution is the reorder point.
The reorder point (also called order point) is the stock level at which a reorder is triggered. No reorder point = no system = gut feeling. And gut feeling works until the first stockout.
Three inventory metrics define your stock management:
The interplay is simple: when stock drops to the reorder point, you reorder. The goods arrive before the minimum stock is reached. Your inventory fluctuates between the reorder point and the maximum stock, without ever running out of material. The IHK Akademie Schwaben puts it clearly: "Professional and efficient warehousing is a decisive competitive advantage. Nobody can be solely responsible for it, since practically all departments share responsibility for stock levels."
Minimum stock, reorder point and maximum stock build on each other. One formula per metric, a clear purpose, a concrete worked example:
| Metric | Formula | Purpose | Worked Example |
|---|---|---|---|
| Minimum stock | Daily consumption × safety factor (days) | Buffer, never to be touched | 20 × 2 = 40 units |
| Reorder point | Daily consumption × lead time + safety stock | Trigger for reordering | 15 × 5 + 30 = 105 coils |
| Maximum stock | Safety stock + optimal order quantity | Upper limit the warehouse should hold | 30 + 200 = 230 coils |
Order of operations: set the minimum stock first (the buffer), then build the reorder point on top (the trigger), finally check the maximum stock (the ceiling). Anyone who sets the reorder point without knowing the minimum stock is guessing two of the three variables.
Three variables, one formula. No higher mathematics, but every variable must be accurate:
1. Daily consumption (units per working day)
The average consumption of an item per day. Not the maximum, not the minimum: the average over a representative period (and no, "roughly 10 units" is not enough). If you want to calculate your daily consumption correctly, you need data from at least 4 to 8 weeks.
2. Lead time (in working days)
The time between placing the order and receiving the goods. Not the lead time printed in the catalogue. The actual, measured lead time across your last orders. Two days according to the quote, but regularly four? Then you calculate with four.
3. Safety stock (minimum stock)
The buffer for everything that can go wrong: supplier delivers late, consumption spikes unexpectedly, goods arrive damaged. The less reliable the supply chain, the higher the safety stock.
An electrical contractor with 6 employees regularly installs NYM-J 3x1.5 cable. The numbers:
Plugging into the formula:
As soon as stock drops to 105 coils, a reorder is placed. The new delivery takes 5 days. During those 5 days, the business uses 75 coils (15 x 5). That leaves 30 coils as buffer. If the delivery arrives on time, the safety stock is never touched.
And the maximum stock? Assume the optimal order quantity is 200 coils:
The logic: you reorder at 105 coils. During the 5-day lead time, you consume 75 coils (15 x 5). When the delivery arrives, you have 30 coils left in the warehouse plus 200 new ones. That tells you: your warehouse needs space for a maximum of 230 coils of this cable type.
The minimum stock is the buffer that is never touched. Without minimum stock, the reorder point has no foundation.
The safety factor is typically 1 to 3 days, depending on delivery reliability.
A plumbing business with 4 technicians uses M8 stainless steel screws daily. The baseline:
As long as at least 40 screws are in stock, the business keeps working even with two days of delay. The reorder point for these screws sits higher:
At 100 screws a reorder is placed, 60 are consumed during the 3-day lead time, 40 remain as buffer.
Deep dive on minimum stock: Formula, calculation and example.
Safety stock is the variable where most businesses get it wrong. Too low: material runs out despite the reorder point. Too high: capital sits idle in the warehouse and warehouse costs rise.
Simplest method: daily buffer. Your supplier is late by an average of 2 days? At 15 units of daily consumption, that is 30 units of safety stock. Does the supplier deliver reliably on the day? Then a half-day buffer is enough.
Three factors determine the level:
The fact is: safety stock is not a static value. Supplier changes = check the buffer. Season starts = check the buffer. Anyone who does not do this is calculating with yesterday's numbers.
Sometimes the lead time is practically zero: you pick up material yourself from the wholesaler, or your supplier has a consignment warehouse on site. In these cases, the formula simplifies:
You reorder as soon as only the buffer remains. This works as long as pickup or resupply is actually possible on the same day.
In practice, a lead time of zero is rare. Even a trip to the wholesaler costs time. And every hour an employee spends fetching material instead of working on site costs real money. That is why it almost always pays to use the full formula.
91 percent of trade businesses see optimized warehousing and logistics as the biggest advantage of digitalization (ZDH/Bitkom, 2017). Yet most still rely on gut feeling instead of metrics (because "we know what we need"). The formula is the easy part. Implementation makes the difference.
Not every item needs a reorder point. Focus on A and B items: material that is consumed regularly and where a stockout has direct consequences. Screws, cable, fittings, pipe clamps. For the specialty item you need twice a year, a simple reminder is enough. Anyone who systematically organizes their warehouse quickly recognizes which items need a fixed reorder point.
Without data, no reorder point. You need actual consumption over at least 4 weeks. Businesses tracking stock on paper can record this manually. Digitally, it is faster and more accurate. Dominik Hartmann, CEO of OneQrew, puts it bluntly: "In this situation, no business can really afford to have employees sacrifice their valuable time to laboriously research alternative items online or phone around to different dealers" (Dominik Hartmann, CEO OneQrew, 2023).
Catalogue lead times are marketing promises. Measure the actual lead time across 5 to 10 orders. The average is your calculation value. The worst case determines your safety stock.
The reorder point only works if someone (or something) monitors the current stock level. Manually, that means: regular warehouse checks. If you want to automate the process, you set up automatic alerts when stock drops below the reorder point.
Consumption changes. Suppliers switch. Order volumes fluctuate. The reorder point you calculated in January may no longer fit in July. Review your values at least quarterly. After every supplier change, immediately.
Three approaches in practice:
Excel spreadsheet (manual). Works for 10 to 20 items, as long as someone maintains it. Problem: Excel does not alert you — you have to actively check. Comparison: Excel vs. digital tools.
Dedicated inventory software. Monitors stock automatically, alerts on breach. For >20 regularly consumed items the more practical route.
Automatic reordering. System triggers the order with the stored supplier. Especially for C-parts (screws, small parts) the biggest time saver.
Some form of monitoring must exist. The best reorder point is useless if nobody is tracking it.
The formula daily consumption x lead time + safety stock takes 30 seconds to calculate. The real effort lies in the three variables: measuring consumption cleanly, estimating lead times realistically, not setting safety buffers based on gut feeling.
Businesses that calculate the reorder point properly for their 10 to 20 most important items and adjust regularly order late less often. That saves emergency runs, downtime and everyone's nerves.
The next step: take your 5 most critical consumables and calculate the reorder point. Daily consumption, lead time, safety stock. Three numbers per item. In 15 minutes, you have a system that makes the difference between "material missing" and "material ready."
How the reorder point method differs from min-max systems depends on your business. Both build on the reorder point but use different triggers. Deep dive: min-max method in detail.
repleno Founder
Christoph worked as an electronics technician in industry for five years and experienced firsthand how missing small parts can slow down processes. Later, as a project manager at P.S. Cooperation GmbH (Böllhoff Group), he introduced digital procurement processes for recurring parts at medium-sized companies and corporations. Today, he is building repleno to largely automate the procurement of consumables in small businesses.
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