Reorder Point Calculator Widget
Help shop owners and buyers know when to reorder. The widget turns average daily demand, supplier lead time and safety stock into a reorder point, and with today's stock on hand shows the days of cover and the days left before the order must go out.
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Under the widget on your page: Powered by A2Z Tools
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<iframe src="https://a2z.tools/embed/w/reorder-point-calculator" title="Reorder Point Calculator by A2Z Tools" width="100%" height="520" style="border:0;width:100%" loading="lazy" allow="clipboard-write"></iframe>
A plain iframe. Works everywhere, including site builders that strip scripts. Adjust height if your content needs more room.
<div data-a2z-widget="reorder-point-calculator" data-height="520"></div> <script async src="https://a2z.tools/embed.js"></script>
Adds a small script (what it does) that sizes the widget to fit its content, loads it lazily and keeps it isolated from your page's CSS.
Works with
How it works
The reorder point is the demand you expect while waiting for a delivery plus a buffer. Average daily demand multiplied by the supplier lead time in days gives the lead-time demand; adding safety stock gives the level at which a replenishment order should be placed. Selling 40 units a day with a 7-day lead time and 60 units of safety stock gives 40 x 7 + 60 = 340 units. The result is rounded up to a whole unit so you never reorder too late. If you enter the stock on hand, the widget divides it by daily demand for days of cover - 500 units last 12.5 days - and works out how many days remain before stock falls to the reorder point: (500 - 340) / 40 = 4 days. When stock is already at or below that level it says so plainly: order now. Lead time can be zero for same-day supply, in which case the reorder point is just the safety stock.
Calculation method
- Lead-time demand = average daily demand x lead time (days)
- Reorder point = lead-time demand + safety stock, rounded up to a whole unit
- Days of stock on hand = stock on hand / average daily demand
- Days until reorder = (stock on hand - reorder point) / average daily demand
Worked examples
Online shop with buffer
Inputs: 40 units a day; 7-day lead time; 60 safety stock; 500 on hand
Result: Reorder point 340; lead-time demand 280; 12.5 days of stock; 4 days until reorder
Place the purchase order in four days, when stock reaches 340.
No safety stock
Inputs: 10 units a day; 5-day lead time; 0 safety stock
Result: Reorder point 50 units
Any delay or demand spike during the five days causes a stockout, which is why a buffer is usually added.
Limitations
- Assumes demand runs at a steady average during the lead time.
- Treats lead time as fixed; variable delivery times call for a statistical safety stock.
- Compares against stock on hand only; open purchase orders and backorders must be adjusted for by hand.
Where publishers use it
- An e-commerce or Shopify seller guide on avoiding stockouts
- Pharmacy and clinic supply blogs managing consumables
- Restaurant and cafe inventory posts for dry goods and packaging
- Maintenance stores deciding when to reorder spare parts
- Inventory-software vendors explaining min/max settings
Questions
Where does the safety stock figure come from?
Either a rule of thumb such as a few days of demand, or a statistical calculation from the variability of demand and lead time with a chosen service level. The companion Safety Stock Calculator does the statistical version: at 95% service, a daily demand of 50 with a standard deviation of 10 and a 7-day lead time needs about 44 units before lead-time variability is added.
Should lead time include my own processing time?
Yes. Use the total time from deciding to order until the goods can be sold or used: raising the purchase order, supplier processing, transit, receiving and putaway. A 5-day supplier quote plus 2 days of internal handling is a 7-day lead time.
Do I compare the reorder point with stock on hand or stock position?
Strictly with the inventory position: on hand plus already on order minus backorders. If an order is already in transit, add it to the on-hand figure before comparing, otherwise you will order twice.
What if demand is seasonal?
Use the average daily demand expected during the coming lead time, not the yearly average. A product that sells 20 a day most of the year but 60 a day in December needs a reorder point three times higher going into the season.
How does a two-bin kanban use the reorder point?
The second bin holds exactly the reorder-point quantity. Pickers empty the first bin, and opening the second one is the signal to reorder - no counting or software needed. For hardware such as screws or labels, a bin sized at 340 pieces does the same job as this calculation.
How is this different from EOQ?
The reorder point answers when to order; the economic order quantity answers how much. Most inventory systems use both: when stock reaches the reorder point, order the EOQ.
Sources
- Inventory Management (DSIS 300 course notes) - University of Kentucky . Gives reorder point = daily demand x lead time + safety stock. Checked 2026-10-01.
- Safety Stock Analysis: Inventory Management Models - A Tutorial - NC State University Supply Chain Resource Cooperative . Reorder point as demand during lead time, with safety stock added for variability. Checked 2026-10-01.
Cite or recommend this tool
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A2Z Tools Reorder Point Calculator https://a2z.tools/inventory-reorder-point-calculator
<a href="https://a2z.tools/inventory-reorder-point-calculator">A2Z Tools Reorder Point Calculator</a>
[A2Z Tools Reorder Point Calculator](https://a2z.tools/inventory-reorder-point-calculator)
Reorder Point Calculator by A2Z Tools - https://a2z.tools/inventory-reorder-point-calculator
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