Margins

A margin is the share of revenue that survives to a given line. Three of them matter, and each answers a different question.

The three

Gross margin = (revenue − cost of goods) ÷ revenue.

What is left after the direct cost of what was sold. This is about pricing power and input costs — whether the company can charge more than the thing costs it.

Operating margin = operating profit ÷ revenue.

What is left after running the business: production, people, marketing, administration. Chapter 4 explained why this is the most comparable line, sitting above financing, tax and depreciation policy.

Net margin = net profit ÷ revenue.

What is left for shareholders after everything. Reflects the business and the capital structure, tax position and any one-offs — which makes it the right number for "what did owners get" and the wrong one for "how good is this business".

Levels mean nothing across industries

A supermarket might run a 3% net margin and a software company 25%. Neither fact says which is the better business.

The reason is chapter 9's: a business turning its capital over many times a year can thrive on a thin margin, while one that turns capital over slowly needs a fat one. Margin alone is half a sentence. Margin times turnover is the sentence, and that is exactly what chapter 10 decomposes.

So compare margins within an industry, never across. A 12% operating margin is excellent in distribution and poor in branded consumer goods.

Direction beats level

The single most useful thing about margins is their trend.

Rising margin usually means pricing power, scale, or a mix shift towards better products. Each is a different story, and the segment note of chapter 4 says which.

Falling margin means competition, input costs, or buying revenue with discounts. The last one is the dangerous one, because it looks like growth at the top line.

That specific pattern — revenue climbing while operating margin slides — is worth isolating. It usually means growth is being purchased. Sometimes deliberately and sensibly, to win a market. Sometimes because the only way to keep growing is to charge less. Chapter 13 is about telling those apart.

Reading a margin change properly

A margin can move for four reasons, and they are not equally interesting.

Price. The company charges more or less. The most informative.

Mix. The same prices, but more of the high-margin product. Real, and dependent on the mix continuing.

Cost. Input prices moved. Often industry-wide and outside the company's control — check a competitor to see.

Volume and fixed costs. More units over the same fixed base lifts margin. This is operating leverage, and it works brutally in reverse: the same fixed costs over fewer units crushes margin in a downturn. A business with high fixed costs has amplified margins in both directions, and a good year tells you less about it than you think.

Three cautions

Compare like with like. Companies define "other expenses" differently and classify costs between heads differently. The trend within one company is more reliable than the level between two.

Watch for capitalisation. Costs capitalised into assets rather than expensed do not hit the income statement this year. Margin improves, and chapter 6's cash flow does not. If margin improves while operating cash flow does not, this is one of the first things to check.

Exceptional items distort. Chapter 4: compute margins before and after them and see which story changes.

What a margin cannot tell you

Whether the company is earning enough on the money invested in it.

A business can run a 20% operating margin and be mediocre, if producing that revenue required enormous capital. That is the question chapter 9 asks, and margin is only one of its two components.

The point

Gross margin is pricing against input cost, operating margin is the business running itself, and net margin is what owners got. Levels are meaningless across industries; the trend within one company is the signal. Revenue rising while operating margin falls usually means growth is being bought.