For example, on very low sales the same behavior is not considered.
You can see from the image that this distribution is symmetrical, that is, you are as likely to sell less than 1000 next month as you are to sell more than 1000 next month.
#ACCURATE STANDARD DEVIATION IN EXCEL DOWNLOAD#
To fully understand this method, you can download the Excel of the example HEREįor example, if you sell an average of 1000 quantities, you have a high probability of selling around 1000 and you have a much lower probability of selling 500 or 2000, for example. Also, this method does not take into account a target service rate based on the type of product or risk of the products I will address in the following methods. I, therefore, advise you to cap the lead time and sales by a percentage for example. The problem is that if you have an extremely long lead time once, for example, it will have a very strong impact on your formula (the same goes for sales). This quite common method has the advantage of being quite simple if you have the data. Safety stock + average sale (or average forecast) x average lead time: This gives us here 1578. Taking the previous data, this gives you a safety stock of 427.įor the order point, it is always the same formula : The formula of this safety stock : (maximum sale x maximum lead time) – (average sale x average lead time).
Then you have had 10 deliveries during these 12 months and the average time is 35 days on average while the maximum time is 40 days (delivery number 4). Your maximum sale per day is 39.5, here you take the month “max” with the formula “max” which you divide by the number of days in a month. On Excel, you have sales over 12 months with a total of 12 000, an average per month of 1000, which makes about 33 pieces per day. You must, therefore, have a stronger safety stock on the umbrella to cover this uncertainty. You will probably have a better forecast quality on toilet paper than on the umbrella. You have very stable products such as toilet paper, and you have much more uncertain products such as umbrellas (which you only sell when it rains). You need a safety stock to cover yourself against two hazards or uncertainties: demand and lead time 1) Demand uncertaintyįor the request, you have different types of products. In this article, I will come back to the main methods I recommend to calculate its safety stock, with always concrete examples of Excel that you can download at the end of this article Why do you need a safety stock?
#ACCURATE STANDARD DEVIATION IN EXCEL HOW TO#
How to calculate your safety stock? By searching on google, you can find dozens of different solutions.
The safety stock (or buffer stock) is the stock level that limits stock shortages due to unforeseen events (forecasts not in line with demand, longer than expected supply time, etc…) Download Excel Safety Stock + Reorder Point.The best solution for inventory management: Machine Learning.How to choose the right formula for your Safety Stock?.Others ways to compute your Safety Stock.Limits of the normal distribution for your safety stock :.
Method 6: Normal distribution with uncertainty on demand and dependent lead time.Method 5: Normal distribution with uncertainty on-demand and independent lead time.Method 4: Normal distribution with uncertainty on the lead time.Method 3: Normal Distribution with uncertainty about the demand.Use constant time units for your calculation.Safety Stock Calculation: 6 different formulas.Safety Stock with EOQ (Economic Order Quantity).