Reorder Point Calculator
Calculate when to reorder stock before you run out.
This tool runs entirely in your browser. Your files are never uploaded to a server.
150 units
Lead time demand
180 units
Reorder point
Reorder when stock on hand drops to this level, so replacement stock arrives before you run out.
What this calculator does
Calculates lead-time demand and a basic reorder point from average daily unit sales, supplier lead time in days, and safety stock in units. The result is the stock level at which this simple model suggests placing an order.
How to use it
Enter average units sold per day, the supplier's order-to-arrival time, and the buffer units you want to hold. Results update immediately; all values must be non-negative and sales and stock must refer to the same unit.
Worked example
With the defaults of 15 units sold daily, 10 lead-time days, and 30 safety units, expected lead-time demand is 15 × 10 = 150 units. Adding the buffer produces a reorder point of 180 units.
Formula used
Lead-time demand equals average daily sales multiplied by lead time in days. Reorder point equals lead-time demand plus safety stock. Both displayed outputs are rounded to whole units even when decimal inputs are supplied.
Choosing the inputs
Estimate daily demand and lead time from a representative history rather than a single order. Safety stock should reflect demand variation, supplier reliability, service targets, seasonality, and the cost of holding excess units.
Limitations
This deterministic formula assumes constant average demand and lead time; it does not calculate statistical safety stock, order quantity, review periods, inbound orders, backorders, multiple suppliers, spoilage, or minimum order constraints.
Interpretation and privacy
Use the result as an operational trigger, then reconcile it with your inventory-position policy and current inbound stock. It is not a guarantee against stockouts. Calculation runs locally in your browser and inputs are not uploaded.
Frequently Asked Questions
- What is safety stock?
- Extra inventory kept as a buffer against demand spikes or supplier delays — it reduces the risk of stockouts.
- How do I estimate my lead time?
- Use your supplier's typical order-to-delivery time, including production and shipping — check past orders for a realistic average.
- What happens if I ignore the reorder point?
- You risk stocking out before new inventory arrives, which can mean lost sales — reordering exactly at this point keeps stock flowing smoothly.