本量利分析法主要关注的是不同程度的活动对于公司财务方面结果方面的影响，之所以把销售量作为一个关键因素是因为在短期，销售价格，原材料以及人工成本常常是可以确定的，然而销售数量通常是不太好预测的。我们常常会问这个问题：“公司将会在这年中盈利吗?”回答是“我们不知道”。我们不知道是因为我们不知道这一年的销售数量，然而，我们能够计算出为了让公司盈利，需要销售多少，因此，本量利分析法就此产生了。

　　以餐厅为例，如果老板能够精确地知道每天晚上会有过少顾客光顾，顾客所点餐的数量以及种类，他们就能够确定雇佣员工的数量以及确保后厨不会有太多的浪费。在现实生活中，例如员工数以及采购量不得不在估计的基础上，这种估计又需要基于以往的经验。在公司开展业务之前最为重要的决策就是需要知道为了达到保本，销售的数量应该是多少?这里的保本意味着没有利润，也没有亏损。这就是我们所知的本量利分析法。

　　Cost–volume–profit (CVP), in managerial economics, is a form of cost accounting. It is a simplified model, useful for elementary instruction and for short-run decisions.

　　LIMITATIONS OF COST-VOLUME?PROFIT ANALYSIS

　　·Cost-volume-profit analysis is invaluable in demonstrating the effect on an organisation that changes in volume (in particular), costs and selling prices, have on profit. However, its use is limited because it is based on the following assumptions: Either a single product is being sold or, if there are multiple products, these are sold in a constant mix. We have considered this above in Figure 3 and seen that if the constance mix assumption changes, so does the break-even point.

　　·All other variables, apart from volume, remain constant, ie volume is the only factor that causes revenues and costs to change. In reality, this assumption may not hold true as, for example, economies of scale may be achieved as volumes increase. Similarly, if there is a change in sales mix, revenues will change. Furthermore, it is often found that if sales volumes are to increase, sales price must fall. These are only a few reasons why the assumption may not hold true; there are many others.

　　·The total cost and total revenue functions are linear. This is only likely to hold a short-run, restricted level of activity.

　　·Costs can be divided into a component that is fixed and a component that is variable. In reality, some costs may be semi-fixed, such as telephone charges, whereby there may be a fixed monthly rental charge and a variable charge for calls made.

　　·Fixed costs remain constant over the 'relevant range' - levels in activity in which the business has experience and can therefore perform a degree of accurate analysis. It will either have operated at those activity levels before or studied them carefully so that it can, for example, make accurate predictions of fixed costs in that range.

　　·Profits are calculated on a variable cost basis or, if absorption costing is used, it is assumed that production volumes are equal to sales volumes.