Inventory Reorder Level Calculator
Know exactly when to reorder each product before it runs out. Enter average daily usage, supplier lead time, safety stock, and current stock for up to 5 products, and the calculator returns the reorder point, safety stock units, a recommended order quantity, days of stock remaining, and a clear stock-out warning.
Your products (up to 5)
Per-product reorder plan
| Product | Safety stock | Reorder point | Recommended order | Days of stock left | Status |
|---|
Reorder point = (daily usage × lead time) + safety stock. Days of stock left = current stock ÷ daily usage.
How the reorder point works
The reorder point (ROP) is the stock level at which you must place a new order so fresh stock arrives before you run out. It covers what you will sell while waiting for the supplier (lead-time demand = daily usage × lead time days) plus a safety stock buffer for surprises like late deliveries or sudden sales spikes.
You can set safety stock two ways: as extra days of cover (for example, 5 extra days of average sales) or as a fixed number of units (for example, always keep 100 units as backup). Days of cover adjusts itself if sales speed up; fixed units stay the same.
- Reorder too late and you face stock-outs, lost sales, and unhappy customers.
- Reorder too early or too much and cash sits idle on shelves while storage costs grow.
- Recalculate monthly: usage changes with seasons, promotions, and new competitors.
Frequently asked questions
What is the difference between reorder point and safety stock?
The reorder point is the trigger level that starts a new purchase order. Safety stock is a smaller buffer hidden inside that level, kept only for unexpected demand or late delivery. You should not consume safety stock in normal sales.
How many days of safety stock should I keep?
A common starting point is 3 to 7 days of average sales. Use more if the supplier is often late or demand jumps suddenly, and less for expensive, slow-moving items where idle cash hurts most.
What should the order quantity be?
Enter your EOQ (economic order quantity) if you know it, or any fixed lot size your supplier requires. If left empty, the calculator suggests one month of average usage as a sensible default order.
What does the stock-out warning mean?
It appears when current stock is at or below the reorder point, which means you should order right away. If stock has also fallen below the safety stock buffer, treat it as critical and expedite the order.