Reorder points are the minimum stock levels that trigger a new purchase order to replenish your inventory. They help you avoid running out of products and losing sales, while also minimizing excess inventory and storage costs. In this article, you will learn how to calculate reorder points for your warehouse operations using a simple formula and some key factors.
The basic formula for calculating reorder points is: Reorder point = (Average daily demand x Lead time) + Safety stock Average daily demand is the number of units you sell or use per day, based on your historical sales data or forecasts. Lead time is the number of days it takes for your supplier to deliver the products after you place an order. Safety stock is the extra inventory you keep on hand to account for fluctuations in demand or supply.
[ \text{Lead Time Demand} = \text{Average Daily Sales} \times \text{Lead Time (days)} ] For example, if you sell 50 units on average per day and your supplier’s lead time is 10 days, your lead time demand will be 500 units.
Finally, add the lead time demand to the safety stock to determine the ROP. [ \text{Reorder Point} = \text{Lead Time Demand} + \text{Safety Stock} ] Using the figures from the examples above: [ \text{Reorder Point} = 500 + 300 = 800 ] units. So, based on these calculations, when your inventory level reaches 800 units, it’s time to place a new order with your supplier.
To estimate your average daily demand, you need to analyze your sales data for a given period, such as a month or a quarter. You can use a spreadsheet or an inventory management software to calculate the total number of units sold or used in that period, and then divide it by the number of days. For example, if you sold 3,000 units in 30 days, your average daily demand is 100 units.
Maintaining perfect data for a quarter will help you to manage the average daily demand. You need to mentain + and - 10% of stocks for a quarter to have the perfect average daily demand.
To determine your lead time, you need to consider the time it takes for your supplier to process, pack, and ship your order, as well as the transit time and any potential delays. You can use your past order history or your supplier's information to estimate the average lead time in days. For example, if your supplier takes 5 days to prepare and ship your order, and the transit time is 3 days, your lead time is 8 days.
To calculate your safety stock, you need to factor in the variability of your demand and supply. You can use the standard deviation method, which measures how much your actual demand or supply differs from the average. The formula for safety stock is: Safety stock = (Maximum daily demand x Maximum lead time) - (Average daily demand x Average lead time) Maximum daily demand is the highest number of units you sold or used in a single day in the past. Maximum lead time is the longest number of days it took for your supplier to deliver your order in the past. For example, if your maximum daily demand is 150 units, your maximum lead time is 12 days, your average daily demand is 100 units, and your average lead time is 8 days, your safety stock is: Safety stock = (150 x 12) - (100 x 8) = 800 units
C’est le stock qui permet de couvrir pendant la période de réapprovisionnement. Stock de sécurité : stock disponible +délai de réapprovisionnement
Once you have estimated your average daily demand, determined your lead time, and calculated your safety stock, you can plug these values into the reorder point formula. For example, if your average daily demand is 100 units, your lead time is 8 days, and your safety stock is 800 units, your reorder point is: Reorder point = (100 x 8) + 800 = 1,600 units This means that you should place a new order when your inventory level reaches 1,600 units or below.
On peut aussi le détermine à partir du la durée moyenne de stockage ( DMS) = nbre de jours de stockage / vitesse de rotation.
Your reorder points are not fixed and may change over time due to changes in demand, supply, or other factors. You should monitor your inventory performance and update your reorder points regularly to reflect the current market conditions and customer preferences. You can use tools like inventory turnover ratio, service level, and stockout rate to measure how well you are managing your inventory and optimize your reorder points accordingly.