What it means
A profit figure on its own tells you very little. Two million dollars of profit is outstanding on $8,000,000 of revenue and disappointing on $200,000,000, which is precisely why analysts convert profit into ratios before drawing any conclusion.
The margin ratios read down the income statement and answer different questions. Gross margin tests pricing and production efficiency, operating margin adds the effect of running costs, and net margin captures everything including interest and tax.
The return ratios compare profit to the capital used to generate it. Return on assets shows how hard the asset base is working, while return on equity shows what shareholders earn on their investment, and the gap between the two is largely explained by how much debt the business carries.
They are used in three main ways: tracking a single company over time, comparing companies within the same sector, and testing whether a business earns more than its cost of capital. Cross-sector comparison is where people go wrong, since a supermarket and a software firm have structurally different margins and neither is better run because of it.
The important nuance is that ratios can be improved by shrinking the denominator rather than growing profit. Selling assets, buying back shares or leasing instead of owning can all lift return on assets or return on equity without the underlying business earning a penny more.
In practice
Real-world examples.
Example
A restaurant group sees revenue rise 18% but operating margin fall from 9% to 6%. The ratios show that growth came from opening sites with higher rents, so the board changes its site selection criteria rather than celebrating the revenue figure.
Example
An investor comparing two engineering firms finds both report a 22% return on equity, but one achieves it with a 14% return on assets and the other with 7%. The second is using far more debt, so its higher risk is hidden behind an identical headline return.
Example
A wholesaler tracking gross margin monthly spots a two-point drop across a single product category. The cause is a supplier price rise not passed through to customers, caught within six weeks instead of at the year-end audit.
Formula
Calculation
Gross margin = gross profit / revenue
Operating margin = operating profit / revenue
Net margin = net profit / revenue
Return on assets = net profit / total assets
Return on equity = net profit / shareholders' equity
A specialist retailer reports the following:
Revenue: $5,000,000
Cost of goods sold: $3,000,000
Gross profit: $5,000,000 - $3,000,000 = $2,000,000
Gross margin: $2,000,000 / $5,000,000 = 40%
Operating expenses: $1,400,000
Operating profit: $2,000,000 - $1,400,000 = $600,000
Operating margin: $600,000 / $5,000,000 = 12%
Interest: $100,000, so profit before tax is $500,000
Tax at 25%: $125,000
Net profit: $500,000 - $125,000 = $375,000
Net margin: $375,000 / $5,000,000 = 7.5%
With total assets of $2,500,000 and shareholders' equity of $1,500,000:
Return on assets = $375,000 / $2,500,000 = 15%
Return on equity = $375,000 / $1,500,000 = 25%
The gap between the 15% return on assets and the 25% return on equity comes from the $1,000,000 of the asset base funded by debt rather than by shareholders.Case study
Seen in the real world.
Marrowfield Textiles is an invented manufacturer used here as an illustrative case study. Its owners were pleased that profit had grown from $600,000 to $780,000 over three years and assumed the business was performing well.
The ratios told a different story. Revenue had grown from $6,000,000 to $10,400,000, so net margin had actually fallen from 10% to 7.5%. Meanwhile the asset base had grown from $4,000,000 to $9,750,000 following a factory purchase, cutting return on assets from 15% to 8%.
The company was getting bigger and less profitable at the same time. Marrowfield introduced a monthly ratio pack alongside its profit report, discontinued two low-margin contract lines, and set a minimum return on assets of 12% for any future capital spending above $250,000.
Watch out
Common mistakes.
- Comparing margins across different industries and concluding that the lower-margin business is badly run, when structural differences in the sector explain the gap.
- Celebrating a rising return on equity that is actually driven by taking on more debt or buying back shares rather than by improved trading.
- Reading a single period's ratios in isolation instead of looking at the trend, which is where seasonality and one-off items get exposed.
Questions
People also ask.
Which profitability ratio matters most?
It depends on the question: gross margin for pricing and production, operating margin for operational control, and return on equity for shareholder returns, so most analysts look at several together.
Why is return on equity usually higher than return on assets?
Because equity is only part of the funding for the asset base, so any profit earned on debt-funded assets above the interest cost accrues to shareholders and lifts the equity return.
Can profitability ratios be manipulated?
Yes, through timing of expenses, capitalising costs rather than expensing them, selling assets or repurchasing shares, which is why the trend and the underlying cash flows matter as much as any single figure.
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