How do you calculate ROE? The formula, a worked example and the three pitfalls

ROE — return on equity — is calculated as the company's net profit after tax divided by its equity, expressed as a percentage. A company that earns a profit of SEK 12 million on equity of SEK 40 million has an ROE of 30 percent. The number answers a single question: how efficiently does the company turn the owners' capital into earnings?

But as with every financial ratio, the calculation is the easy part — interpretation is the art. ROE can look impressive for entirely the wrong reasons, and three specific pitfalls account for most of the misunderstandings. We take them in turn, after the arithmetic itself.

The formula — one division and nothing more

ROE = Net profit after tax ÷ Equity × 100

Both figures are found in the annual report. Net profit is the bottom line of the income statement — after net financial items and tax. You find equity on the balance sheet: share capital, restricted reserves and free liquidity, minus any stocks the company holds in itself.

A matter of practice: do you use equity at year-end or the average of the beginning and end of the year? The average is right if the company has built up capital during the year — otherwise growth companies that retain profits in the business are penalized. Always compare companies using the same calculation practice, otherwise the numbers are not comparable.

The worked example: two companies, the same profit

Imagine two companies that both report SEK 12 million in net profit:

• Company A: equity of SEK 40 million. ROE = 12 ÷ 40 = 30 percent.
• Company B: equity of SEK 120 million. ROE = 12 ÷ 120 = 10 percent.

The same profit, a threefold difference in measured efficiency. Company A squeezes more earnings out of every owner's krona; Company B rests on a heavy capital base. Neither number is "better" in absolute terms — they describe two different business models. That is why ROE should always be read against industry peers, not against a universal target.

The DuPont decomposition: where the return comes from

ROE can be broken down into three components — the classic DuPont identity:

ROE = Profit margin × Capital turnover speed × Capital structure (leverage)

• Profit margin (net profit ÷ revenue) — how much of every sales krona is left over.
• Capital turnover speed (revenue ÷ total assets) — how hard the assets work.
• Leverage (total assets ÷ equity) — how much of the balance sheet is financed with debt.

The decomposition reveals the story behind the number. Two companies with 20 percent ROE are not the same thing if one gets there through a 15 percent profit margin and the other through heavy borrowing. Margin quality is sustainable; leverage quality is cycle-dependent. In the AKM1 model, that is why ROE is always read together with V10 (debt-to-equity ratio) and V19 (capital burn) — return and risk are two sides of the same balance sheet.

Pitfall 1: leverage masquerading as efficiency

Because leverage is a multiplicative component of ROE, a company can raise the number simply by borrowing more. Equity shrinks, the division yields a higher figure — the business is unchanged. The check: also calculate return on total capital (net profit plus after-tax interest costs, divided by total assets). If ROE rises while total return stands still, the improvement is debt-financed, not operational.

Pitfall 2: the shrunk equity

Large share buybacks and extraordinary depreciation can push equity toward zero — and a small denominator mechanically inflates ROE. In the extreme, the denominator turns negative and the financial ratio becomes meaningless. The check: follow the development of equity over five years, not just the last balance-sheet date. Equity that eats itself is not a sustainable ROE engine.

Pitfall 3: one-off items in the earnings

The sale of an asset, a tax effect or a divestment can lift net profit in a given year. The check: go to the cash flow side and compare earnings with the cash flow from ongoing operations. Booked profit without a corresponding cash flow deserves a close reading of the notes — the accruals leg of the Piotroski F-score captures exactly this pattern.

The industry check: what is normal

Descriptively, without moralizing: banks often sit around 10–15 percent (regulated leverage), mature manufacturers around 10–20 (capital heavy), software companies can sit significantly higher (light balance sheets), and real estate companies vary sharply with the valuation cycle. The comparison group defines the interpretation — an 8-percent ROE in an industry where the median is 6 is a different story from the same number among companies at 18.

The full ROE deep dive is in the Curriculum: the V09 course walks through the calculation, DuPont and industry adjustment with Swedish examples.

The exercise: run the formula on a real annual report

1. Open the latest annual report of a company you follow. 2. Read off net profit and equity — calculate ROE for the three most recent years. 3. Decompose with DuPont: which of the three components is driving? 4. Enter the figures in the calculator and see how the financial ratio positions against the industry median.

Fifteen minutes, four numbers — and you know more about the company than most headlines tell.

Next steps

• Go deeper into where the ROE page belongs in the Curriculum: the V09 course ties the financial ratio to earnings quality and capital structure.
• Test the pitfalls in practice: the calculator computes the DuPont decomposition automatically.
• See the whole context in the portfolio builder: ROE is one of the voices, never the whole choir.

FAQ

How do you calculate ROE?

Net profit after tax is divided by equity and multiplied by 100. A company with 12 million in profit and 40 million in equity gets ROE = 12 ÷ 40 = 30 percent — both figures are found directly in the annual report's income statement and balance sheet.

What is DuPont decomposition?

A method of breaking ROE into three components: profit margin, capital turnover and leverage. The decomposition shows where the return actually comes from — margin-driven ROE is sustainable, while leverage-driven ROE is cycle-dependent.

What is a normal ROE level?

It depends on the industry: banks often move around 10–15 percent, mature manufacturers around 10–20, and capital-light software companies can sit considerably higher. ROE should therefore always be read against the industry median, never against a universal target.

This is educational financial analysis, not investment advice.