The determination of purchasing quantity can not only rely on the psychological estimation of purchasing personnel, but also must be based on certain systematic knowledge, and many small shop entrepreneurs who have been carefully considered and calculated by purchasing personnel will think that purchasing in large quantities is the secret to reducing costs, but this method is not feasible in some industries. The determination of the purchase quantity can not only rely on the psychological estimation of the purchaser, but also must be based on certain system knowledge and various factors carefully considered and calculated by the purchaser. Usually, before purchasing, the purchaser should predict the sales of each commodity in a certain period of time. If the forecast is as detailed as possible, the quantity error in the final sales plan will be very small, thus reducing the inventory burden of the store. For example, if you manage fashion, the popularity of fashion determines the timeliness of sales. Small shop entrepreneurs should pay attention to controlling the appropriate quantity when purchasing goods, and demand quality rather than quantity in terms of color and style. Doing so can not only ensure the characteristics of the store, but also relieve the pressure on funds and inventory. Generally speaking, there are the following methods to confirm the purchase quantity. 1. Purchase according to the validity period of commercial crystal storage. Applicable industry: catering industry. The control of the validity period of food in catering industry is one of the important methods to ensure the quality. Therefore, the storage validity period should not be neglected when purchasing, that is to say, the consumable period of the total amount of purchased goods should not exceed the storage validity period. 2. Purchase applicable industries according to the expected turnover: all types of small shops. The level of turnover directly affects the purchase volume of goods. Therefore, when purchasing, the primary consideration is what business you intend to do, that is, to estimate the turnover, so as to deduce how many raw materials you need to prepare. The calculation elbow can be based on the average value of raw materials consumed per unit turnover, and then the demand for raw materials when the estimated turnover is reached can be calculated. 3. Purchase applicable industries according to the length of supply period: fashion commodity industries. When purchasing, we also need to consider the length of the supplier's delivery period, that is, how long it will take to deliver the goods after accepting the order, and when is the next delivery. Because the arrival time or delivery time of the goods provided by each supplier is different, it is necessary to order enough goods according to the delivery time when purchasing. 4. Purchase applicable industries according to the usage of raw materials: processing industries. The past use of various raw materials in a small shop can also be used as an important reference for procurement. Under normal circumstances, it is very important to use the consumption of the previous period as the basis for the next purchase, and pay attention to the long-term cumulative record of the consumption of various raw materials. 5. Purchasing applicable industries according to regional characteristics: clothing industry. For chain stores, each branch can take the characteristics of the location business circle as the basis for estimation, procurement or management indicators. However, uncontrollable is always there, and many situations are unpredictable. Therefore, a good purchaser must be highly alert to abnormal situations. Check the inventory, usage and purchase of important raw materials daily to determine the normality of frequency. After the abnormal situation occurs, we should try our best to understand the causes, track the consequences and record them as the basis for future reference. 6. Purchase applicable industries according to the inventory results: all types of small shops. Applicable industries: catering industry. When deciding how much quantity to order, the last thing to pay attention to is that the packaging capacity of these goods must be considered and adjusted appropriately. Not all goods are directly led by purchasing personnel, and some goods are limited to professional or other reasons. The store entrepreneurs or warehouse managers should draw up purchase orders according to their requirements and safe inventory, which will be approved by the store entrepreneurs, and finally the purchasing personnel will directly handle the procurement matters. For the catering industry, due to the influence of season, climate, output, price, promotion and other factors, some ingredients really can't apply the formula to calculate the accurate purchase quantity, but generally the best purchase quantity can still be obtained according to the formula. 8. Purchase applicable industries according to seasonal changes: gift industries and holiday industries. The change of seasons and weather will often affect the usage of dishes and raw materials. At the same time, more importantly, these changes are the most important indicators of fresh food supply period, output, quality and price. Purchasing staff need to cooperate closely with sales staff in order to achieve the highest benefit of purchasing. 9. Purchase according to advertising promotion. Applicable industries: all types of small shops. In order to improve operational performance, or enhance competitiveness, or stimulate customer consumption, nowadays, small shops pay more and more attention to advertising promotion. Because advertising promotion often breaks the normal proportion of the original commodity consumption, buyers need to know more about the content, target and expected goal of the store, and adjust the purchase quantity appropriately to cooperate with the promotion activities. These are the nine principles that need to be followed in purchasing. As for the procurement cycle, in theory, the shorter the better. However, considering the factors such as freshness, consumption, smell of supply and inventory shortage, the procurement cycle of various raw materials is not the same, and general goods can be purchased once a month. However, the catering industry must have a detailed plan in this regard, such as purchasing fresh meat, fruits and vegetables once a day, and purchasing frozen food once a week or every twenty days.