Net profit margin is net income divided by revenue for the same period, expressed as a percentage. It says how many cents of profit the period produced for every dollar of revenue, after the cost of what was sold, operating expenses, interest and income tax expense. Net income margin and net margin name the same ratio.
The Formula
Both inputs come off one income statement covering one period.
net profit margin = net income / revenue x 100Net income is the bottom line of that statement, and the order the subtractions run in to get there is set out in net income. Revenue is the top line the same statement opens on, which on a filed statement of comprehensive income is the caption for net sales and gross revenues (17 CFR 210.5-03).
A Worked Example
Say a firm closes a year on the revenue and bottom line below, with every expense of the period already subtracted between them.
Revenue 500,000
Net income 79,000
Net profit margin 79,000 / 500,000 = 15.8%The percentage compresses every line in between into one number, so two firms can land on the same margin with different cost structures behind it.
What the Ratio Depends On in a Firm’s Work
Both inputs are outputs of the close rather than inputs to it, so the margin is only as good as the close that produced it. An unbooked accrual, an unreconciled bank account or a cost sitting in the wrong period moves net income, and the margin moves with it. The sequence that gets a statement to that point is in the month-end close checklist.
It is a ratio of a period and not a reading at a date. Revenue and net income both cover a stretch of time, which is what an income statement reports, so a margin for a stub period and a margin for a full year answer different questions and do not sit side by side.
The margin is also computed on net income as accrual accounting measures it, so a strong percentage on its own says nothing about the bank balance. Revenue counts on delivery rather than on payment, and the amount still waiting to close that gap sits in accounts receivable.
What Net Profit Margin Is Not
Gross Margin
Gross margin is gross profit over revenue, though the same words also name the dollar subtotal that ratio is built on, and that subtotal sits well above the bottom line. The line that subtracts the costs of sales from net revenues produces a subtotal called gross profit, or sometimes gross margin, and it is gross because there are certain expenses that have not been deducted from it yet (SEC, Beginners’ Guide to Financial Statements). Operating expenses, interest and income tax are all still ahead of it, and net profit margin is measured after all three.
Operating Margin
Operating margin is income from operations divided by net revenues, calculated before interest and income tax expenses (SEC, Beginners’ Guide to Financial Statements). The two margins therefore diverge on any period that carries either one.
Markup
Markup is figured on cost and margin is figured on revenue, which is why one profit produces two different percentages. The same Treasury regulation uses both words in one section: under the resale price method the gross profit margin is expressed as a percentage of total revenue derived from sales, and under the cost plus method the gross profit markup is expressed as a percentage of cost (Treasury Regulation 1.482-3). Reading a markup as though it were a margin overstates profitability, because on a profitable sale cost is the smaller base.
Common Questions
There is no single figure. Desirable ratios vary by industry as a general rule, which is the qualification the SEC’s guide to reading financial statements puts on the ratios investors compute from them (SEC, Beginners’ Guide to Financial Statements). A margin only reads as good or bad against firms with a comparable cost structure over a comparable span of dates.
Accountably places trained offshore accountants and tax preparers inside US CPA and EA firms, and a trial task lets a firm grade a real block of its own close work before anything client facing depends on it.
