Inventory Reorder & Safety Stock Calculator
Work out your reorder point and safety stock so you never run out of bestsellers or overstock slow movers.
How the Inventory Reorder Calculator Works
Run out of a bestseller and you lose sales and ad momentum. Order too much and cash sits on a shelf. The reorder point tells you exactly when to place your next supplier order so new stock arrives just before the old stock runs out.
Enter your average daily sales and your average supplier lead time. Add your maximum daily sales and maximum lead time to size a safety stock buffer. The tool shows your reorder point, safety stock, and the demand you expect while waiting for delivery. If you also enter your current stock, the result card turns red when it is time to reorder and green when you are above the reorder point.
Key Formulas Behind This Tool
- Demand During Lead Time: Average Daily Sales x Average Lead Time
- Safety Stock: (Maximum Daily Sales x Maximum Lead Time) - (Average Daily Sales x Average Lead Time)
- Reorder Point: Demand During Lead Time + Safety Stock (rounded up)
- Days of Stock Left: Current Stock on Hand / Average Daily Sales
Frequently Asked Questions (FAQ)
What is a reorder point?
The reorder point is the stock level at which you should place a new supplier order. It equals the demand you expect during the supplier lead time, plus safety stock to cover surprises.
What is safety stock?
Safety stock is the extra inventory you keep to cover sales spikes or late deliveries. This tool calculates it as maximum daily sales times maximum lead time, minus average daily sales times average lead time.
What should I enter for maximum daily sales and maximum lead time?
Use your busiest realistic sales day (for example during a promotion) and the longest delivery time your supplier has taken in the past year. If you leave them blank, the tool uses your averages and safety stock becomes zero.
How do I find my average lead time?
Count the days between placing a purchase order and having the stock available to sell, including production, shipping, customs, and receiving. Average the last several orders.
Why does carrying too much safety stock hurt?
Extra inventory ties up cash, takes up warehouse space, and adds storage fees. The goal is enough buffer to avoid stockouts without freezing money in slow-moving units.