Safety Stock and Reorder Point Calculator

Safety stock is the extra inventory you keep on hand to protect against unexpected spikes in demand or delays in supplier delivery.

Reorder Point is the inventory level at which you should place a new order. The formula is: Reorder Point = (Average Daily Demand × Average Lead Time) + Safety Stock

Together, these two numbers help you maintain the right inventory levels… avoiding stockouts while preventing excess stock that ties up cash.

Two Calculation Methods

We’ve provided two different methods in the single calculator below so you can choose the one that best fits your data:

• Simple (Maximum vs Average) Method

  • Best for beginners or when you have limited historical data. This method is conservative, so it will recommend higher levels of safety stock than the statistical method.

  • This method uses the formula Safety Stock = (Maximum Daily Demand × Maximum Lead Time) − (Average Daily Demand × Average Lead Time)

• Statistical (Service Level) Method

  • Best for businesses with sales history who want a more precise, data-driven result.

  • This method uses the formula: Safety Stock = Z × Standard Deviation of Daily Demand × √Lead Time

How to Choose A Safety Stock Calculation Method

• Use the Simple Method if you’re just starting out or prefer a quick, cautious estimate.

• Use the Statistical Method once you have enough sales data for better accuracy and lower holding costs.

Expert Tip: Many businesses begin with the Simple method and switch to Statistical as they grow. You can run both and use the results as a helpful range.

Scroll down to use the combined Safety Stock & Reorder Point Calculator. If you need help interpreting the results, calculating standard deviation, or applying these numbers to your products, feel free to reach out!