性价比是商品的性能值与价格值比，是反映物品的可买程度的一种量化的计量方式。性价比全称是性能价格比，是一个性能与价格之间的比例关系，具体公式：性价比=性能/价格。
Cost-effectiveness is the ratio of the performance value of a commodity to its price value. It is a quantitative measurement method that reflects the degree of purchase of an item. The full name of cost-effectiveness is performance-price ratio, which is a proportional relationship between performance and price. The specific formula is: cost-effectiveness = performance/price.
通常不会在同一性能基础上比较或比较的机会较少。性价比应该建立在你对产品性能要求的基础上，也就是说，先满足性能要求，再谈价格是否合适，由于性价比是一个比例关系，它存在其适用范围和特殊性，不能一概而论。
在购买某个商品过程中或多或少都需要了解，商品品质好、价格低，性价比高。所以，许多顾客都把性价比看成是选购商品的重要指标。
人们购买产品时，都会选择性价比高的产品购买。但是，产品的性价比应该建立在相同的性能基础上，也就是说：如果没有一个相同的性能作为比较基础，得出的性价比是没有意义的。
性价比存在了一个很大的漏洞。根据性价比的公式，可以知道性价比不是一个固定的数值，只是一个比例关系。一般来说：性价比高，性能相同、价格低；性能高、价格相同。性价比低，性能相同、价格高；性能低、价格相同。
但是性价比不是一成不变的。
性价比增加的一个典型事例是当今电子商品和信息产品，随着科技的进步，电子商品的性能上升飞速，但由于制造水平的提高及成本的下跌，同型号产品的价格不断下跌，造成了性价比的提高。 所以，在购买过程中，商家强调某个产品与某某产品比较，价格如何超值、性价比超高，你就要小心了，说不定这个大馅饼对你来说是个大陷阱；还有，当产品价格变化时，不但要注意产品价格变化时，还要注意产品性能的变化（整体质量、配件数量等），具体来说，发现价格变化时，要搞清楚为什么会变化，变化的主要原因在哪里，是工艺改进、促销、清货还是其他什么的原因，不要让性价比把你迷惑了。
Usually, there is no comparison or fewer opportunities for comparison on the same performance basis. Cost-effectiveness should be based on your requirements for product performance, that is, first meet the performance requirements, and then talk about whether the price is appropriate. Since cost-effectiveness is a proportional relationship, it has its scope of application and particularity, and cannot be generalized.
In the process of purchasing a certain commodity, it is more or less necessary to understand that the product has good quality, low price, and high cost-effectiveness. Therefore, many customers regard cost-effectiveness as an important indicator for purchasing commodities.
When people buy products, they will choose products with high cost-effectiveness. However, the cost-effectiveness of the product should be based on the same performance, that is, if there is no same performance as a comparison basis, the cost-effectiveness obtained is meaningless.
There is a big loophole in cost-effectiveness. According to the formula of cost-effectiveness, it can be known that cost-effectiveness is not a fixed value, but a proportional relationship. Generally speaking: high cost-effectiveness, same performance, low price; high performance, same price. Low cost-performance ratio, same performance, high price; low performance, same price.
But cost-performance ratio is not static.
A typical example of increased cost-performance ratio is today’s electronic products and information products. With the advancement of technology, the performance of electronic products has risen rapidly, but due to the improvement of manufacturing level and the decline in costs, the prices of products of the same model have continued to fall, resulting in an increase in cost-performance ratio. Therefore, in the purchase process, if the merchant emphasizes how a certain product is compared with a certain product, how the price is super value and how cost-performance ratio is super high, you should be careful, maybe this big pie is a big trap for you; also, when the product price changes, you should not only pay attention to the change of the product price, but also pay attention to the change of product performance (overall quality, number of accessories, etc.). Specifically, when you find that the price has changed, you should figure out why it has changed and what the main reason for the change is, whether it is process improvement, promotion, clearance or something else. Don’t let the cost-performance ratio confuse you.