Understanding Reorder Points and Safety Stock in Inventory Planning

What is reorder point and safety stock?

Screenshot of Obius SaaS Platform

In the fast-paced world of e-commerce, efficient inventory management is crucial to ensuring customer satisfaction and maintaining optimal stock levels. For Shopify store owners, especially those managing significant inventory, understanding key concepts like reorder points and safety stock is essential. These concepts help in avoiding stockouts and overstock situations, ensuring smooth operations. Let's dive into what reorder points and safety stock are, and how they can benefit your inventory planning.

What is a Reorder Point?

The reorder point (ROP) is a specific inventory level that signals when it’s time to place a new order for more stock. This threshold ensures that new inventory arrives before your current stock runs out. Calculating the ROP accurately is vital to maintaining sufficient inventory levels and avoiding disruptions in supply.

Components of Reorder Point:

  1. Average Daily Usage: The average number of units sold or used per day.
  2. Lead Time: The time it takes for an order to be delivered once it's placed.
  3. Safety Stock: Additional inventory kept to buffer against uncertainties in demand and supply.

Formula for Reorder Point:

Reorder Point Formula:

\[ \text{ROP} = (\text{Average Daily Usage} \times \text{Lead Time}) + \text{Safety Stock} \]


\[ \begin{align*} \text{Average Daily Usage} = 2 \, \text{units/day} \\ \text{Lead Time} = 15 \, \text{days} \\ \text{Safety Stock} = 3.81 \, \text{units} \end{align*} \]

Calculate Reorder Point:

\[ \text{ROP} = (2 \times 15) + 3.81 \]


\[ \text{ROP} = 33.81 \, \text{units} \]

By incorporating both average daily usage and safety stock, the ROP ensures you place orders just in time to replenish your inventory without running out of stock.

Calculate Reorder Point (ROP):

Reorder Point:

What is Safety Stock?

Safety stock is the extra inventory kept on hand to protect against variability in demand and supply chain disruptions. It acts as a buffer, ensuring that even if there are unexpected spikes in demand or delays in replenishment, your stock levels remain adequate to meet customer needs.

Components of Safety Stock:

  1. Demand Variability: The fluctuation in daily demand for a product.
  2. Service Level: The desired probability of not experiencing a stockout during the lead time.
  3. Lead Time Variability: The variability in the time it takes to receive new inventory (if applicable).

Formula for Safety Stock:

A common method to calculate safety stock involves using the standard deviation of demand and a service level factor (z-score):

Safety Stock Formula:

\[ \text{Safety Stock} = Z \times \sigma_d \times \sqrt{LT} \]


\[ \begin{align*} \text{Desired Service Level} = 95\% \quad (Z = 1.645) \\ \text{Standard Deviation of Daily Demand} (\sigma_d) = 0.6 \, \text{units} \\ \text{Lead Time} (LT) = 15 \, \text{days} \end{align*} \]

Calculate Safety Stock:

\[ \text{Safety Stock} = 1.645 \times 0.6 \times \sqrt{15} \]


\[ \text{Safety Stock} \approx 3.81 \, \text{units} \]

Calculate Safety Stock:

Safety Stock:

Reorder Point Strategies

Implementing effective reorder point strategies is key to maintaining optimal inventory levels. Here are a few strategies to consider:

1. Regularly Review and Adjust Reorder Points

Demand patterns and lead times can change, so it’s important to regularly review and adjust your reorder points:
Periodic Reviews: Conduct periodic reviews of your reorder points based on sales data and changes in lead times.
Seasonal Adjustments: Adjust reorder points for seasonal products to account for higher or lower demand during specific times of the year.

2. Use Automated Inventory Management Tools

Automating the calculation and monitoring of reorder points can save time and reduce errors:
Inventory Management Software: Utilize inventory management software that integrates with Shopify to automate reorder point calculations.
Real-Time Tracking: Implement real-time tracking to ensure your reorder points are always based on the most current data

3. Buffer for Uncertainty

To account for unexpected spikes in demand or supply chain disruptions, build in a buffer to your reorder points:
Safety Stock: Always include safety stock in your reorder point calculations to protect against variability.
Emergency Stock: Consider maintaining a small emergency stock for critical items that have high demand variability or longer lead times.

Benefits of Using Reorder Points and Safety Stock

1. Prevent Stockouts: Ensures you have enough inventory to meet demand, reducing the risk of stockouts.
2. Optimize Inventory Levels: Helps maintain optimal inventory levels, avoiding both overstock and understock situations.
3. Improve Customer Satisfaction: Reliable stock levels lead to better service and customer satisfaction.
4. Streamline Operations: Automated reorder points simplify the reordering process, saving time and effort.

Implementing These Concepts in Your Shopify Store

Our Shopify app for inventory planning makes it easy to calculate and manage reorder points and safety stock. By integrating real-time sales data and using advanced algorithms, our app provides accurate reorder recommendations tailored to your business needs. 


Understanding and implementing reorder points and safety stock is crucial for efficient inventory management. These tools help you maintain optimal stock levels, prevent stockouts, and ensure customer satisfaction. By leveraging our Shopify app, you can automate these calculations and focus on growing your business with confidence.Ready to optimize your inventory? Explore our Shopify app today and take the guesswork out of inventory planning!For more tips on efficient inventory management and to see how our app can benefit your Shopify store, visit our website or contact our support team.

Let’s keep your shelves stocked and your customers happy!

Get in touch!

Let us know how we can help