Reorder point & safety stock calculator

Safety stock is extra inventory that covers days when you sell more than usual, or when a supplier is late. It is usually worked out from the gap between your busiest day and your average day, multiplied by the lead time.

Take the units sold over a month and divide by 30. If your business is quiet on some days and busy on others, use a busier-period figure for the max daily sales so your safety stock covers your peaks.

It depends on how badly you lose money when the product runs out. For essentials your customers will buy elsewhere the moment stock is gone, keep a bigger buffer. For slow-moving items, a smaller one is fine so you do not tie up cash in stock.

Usually one of three reasons: your lead time is longer than you think, you order too late, or you forget your busiest days. Check the lead time your supplier actually takes, then order as soon as stock crosses the reorder point - not when you notice it is empty.

Yes. Products sell at different speeds and have different suppliers, so a blanket rule like "reorder everything at 50 units" overstocks slow items and understocks fast ones. Run the calculator once per fast-moving product and you will have a simple reorder list.

Multiply your average daily sales by the supplier lead time, then add safety stock. Selling 20 units a day with a 7-day lead time and 105 units of safety stock gives a reorder point of 245 units. Place the order the moment stock falls to that level.

Enter your current stock on hand and compare it with the reorder point. Below the reorder point the calculator says "Reorder now", and at or below safety stock it says "Critical - order immediately". Above it, you see how many days of cover remain and can plan the next order.

The calculator divides your stock on hand by your average daily sales to give days of cover. With 140 units and 20 sold a day, you have 7 days of cover left. It also shows the days before you cross the reorder point, so you can judge whether a delivery will land in time.

Enter the lead time delivery actually takes, not the one promised, and keep a larger safety buffer. Safety stock is the gap between your busiest and average daily sales multiplied by the lead time, so a longer or more unpredictable lead time pushes both the safety stock and the reorder point higher.

Your safety stock is built from the gap between your maximum and average daily sales times the lead time. If your busiest day is far above your average, or your lead time is long, the buffer grows - and if you understate either number, the buffer undershoots real peaks. Update the inputs whenever your trading pattern changes.