比如：收入是100， 成本是80，則毛利（gross profit）是20，扣除其他稅費之後凈利潤（net profit）假設是10，那麽毛利率（Gross profit margin）=20/100=20%，凈利率（Net profit margin）=10/100=10%。
以下是英文版詳細解釋：
Margin is used to compare A relative to B, where A is part of B. Margin is usually stated as a percentage.
Followings are two examples of margins:
1. Gross profit margin = Gross profit / revenue;
2. Net profit margin = Earning after tax / revenue;
In accounting, a simple expression of a profit and loss statement is as follows:
Revenue 1,000
Cost of good sold -900
Gross PROFIT 100
Operating expenses -10
other expenses -2
tax -3
net PROFIT after tax 85
then, Gross profit MARGIN = 100/1000 = 10%.
Net profit MARGIN = 85/1000 = 8.5%
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PROFIT is a certain amount of benefit obtained from operations of a company or from trading activities. Different from a margin, profit is stated in a full monetary value. In the above example, the gross profit MARGIN is 10% but the Gross PROFIT is 100; and net profit MARGIN is 8.5% but the Net PROFIT after tax is 85.