In eCommerce, where customer satisfaction hinges on the seamless availability of products, mastering inventory management is necessary. A staggering 4% of annual sales are lost on average due to stockouts, yet overstocking, while appearing as a safety net, can silently erode your profits with rising holding costs. This is where Re-Order Point (ROP) becomes a game-changer for eCommerce brands.


ROP signifies a critical juncture in your stock levels where hitting the reorder button ensures you’re perfectly balancing demand satisfaction and cost-effective inventory holding. For eCommerce businesses, where every square foot of warehouse space and every minute of delivery time counts, understanding and implementing ROP can be the difference between thriving and merely surviving.


Understanding What is Re-Order Point?


The concept of ROP in eCommerce transcends the traditional approach of merely filling shelves. Here, it morphs into a strategic tool vital for keeping your digital storefront stocked and ready. ROP is that pivotal inventory level that signals the time to replenish stock. It strikes a delicate balance between having enough to meet demand and not so much that your storage is overflowing with unused products.


Like MOQ, it gives the minimum quantity of units that businesses are willing to sell, a well-calculated ROP ensures that you’re never caught off guard. It’s a number based on precise calculations – a blend of your average sales velocity, the lead time from your suppliers, and a cushion of safety stock to cover unexpected spikes in demand or supply chain hiccups.


The impact of ROP on customer satisfaction is profound. In an era where next-day (or even same-day) deliveries are becoming the norm, having the right product at the right time is paramount. ROP helps you achieve just that, ensuring that your customers’ desired products are always a click away from being dispatched.



The Formula of Reorder Point (Calculating ROP)


At its core, the ROP formula is a blend of careful calculation and strategic foresight. It hinges on two primary versions, each catering to specific inventory management needs.


Formula 1

ROP = (Average Daily Usage × Average Lead Time in Days) + Safety Stock


In this first formula variant, Average Daily Usage is a metric that tracks the daily movement of your products. This figure is multiplied by the Average Lead Time in Days – from initiating an order to when it is received and ready for sale. This multiplication gives you the Lead Time Demand that reflects the quantity of stock that will be consumed. Including Safety Stock – that essential buffer against the unpredictable elements of demand and supply – adds another layer of security.


Formula 2

ROP = Lead Time Demand + Safety Stock


The second formula variant simplifies the calculation by focusing directly on Lead Time Demand. This version is particularly useful when Average Daily Usage is subject to fluctuations or when detailed data on daily usage isn’t readily available. Lead Time Demand is a predefined figure based on historical sales data, market analysis, or predictive modeling.



Components of Re-Order Point Calculation


1. Daily Sales Velocity


Daily Sales Velocity is the average number of units of a product sold per day. This metric acts as the pulse of your inventory, reflecting the steady rhythm of your sales.


2. Lead Time


Lead Time in the ROP calculation refers to the time it takes from placing an order with your supplier to having the product ready for sale. The thread connects your stock levels to your supplier’s efficiency.


3. Safety Stock


Safety Stock is the additional quantity of an item held in the inventory to reduce the risk of stockouts caused by fluctuations in demand and supply.



Step-by-Step Process to Calculating Re-Order Points


1. Identifying the Average Demand


Average Demand represents your product’s life cycle. It’s a measure of how many units of a product are sold on average. This metric is crucial in the ROP calculation as it directly impacts when you’ll need to reorder to meet customer demands. For example, imagine you’re selling artisan coffee beans. Over the last 30 days, you sold 900 bags. Thus, your average daily sales would be 900 divided by 30, equating to 30 bags per day.



2. Calculation of Your Supplier’s Lead Time


Lead Time in inventory management is the time taken from placing an order with a supplier to when it’s received and ready for sale. It’s a critical factor as it determines how soon you need to place an order before stock runs out. Check with your suppliers for their estimated delivery times. Also, do not forget to review past orders to gauge actual lead times, noting any delays or early deliveries. For example, for your coffee beans, let’s say your supplier typically takes ten days to deliver an order. Hence, your lead time is ten days.


3. Decide if Safety Stock is Necessary or Not


Safety Stock is your emergency reserve, a buffer to protect against sudden demand spikes or supply delays. It’s a critical component of the ROP calculation, ensuring you don’t run into stockouts. To determine safety stock, review your sales data for the highest demand periods and determine how much stockout risk you’re willing to tolerate. Then, assess the reliability of your suppliers. More unreliable suppliers necessitate higher safety stock.


4. Use the Reorder Level Formula


Select the formula based on the predictability of your sales and the reliability of your type of supply chain. Formula 1 suits more stable scenarios, while Formula 2 is better for varying sales patterns.


Formula 1: ROP = (Average Daily Usage × Average Lead Time in Days) + Safety Stock.

For our coffee beans: ROP = (30 bags × 10 days) + 150 bags = 450 bags.


Formula 2: ROP = Lead Time Demand + Safety Stock.

Assuming your lead time demand is 300 bags: ROP = 300 bags + 150 bags = 450 bags.


5. Assess and Adjust as Required


Sales Tracking: Regularly track sales to detect changes in demand. Monitor supplier performance for any shifts in lead times and stay attuned to market trends that could affect sales. Reassess your ROP quarterly or in response to major market changes.


Data-Driven Decisions: Use analytics tools to make informed adjustments.





The adoption of ROP methodologies is essential for eCommerce businesses aiming for long-term success. It allows for agile responses to market changes, supports data-driven decision-making, and fosters a proactive approach to logistics management.


Looking ahead, as technology advances, integrating ROP with predictive analytics, AI, and machine learning will provide even more accurate and dynamic supply chain management solutions. You can do this now with NimbusPost’s advanced warehouses and fulfilment centers. The integration with NimbusPost warehouses will enable eCommerce businesses to stay ahead of trends, anticipate customer needs, reduce delivery costs, enable faster deliveries, and navigate the complexities of global supply chains with greater confidence and foresight.





What is the difference between reorder level and EOQ?


A reorder level is the point at which a business orders new stock from a supplier. Economic order quantity (EOQ) is a calculation that determines the optimal order size to meet demand without overspending.


What is the reorder point in MRP?


In MRP, a reorder point (ROP) is the minimum number of units of an item that a company should have in stock to avoid running out. ROP is also known as the Ordering Point (OP).

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