What return on equity measures
Return on equity answers the owner's question: for every dollar of my capital sitting in this business, how much profit did it make this year? Book equity is the money shareholders put in plus every dollar of profit the company kept rather than paid out, so ROE measures the return on the whole accumulated stake, not just on the original investment.
That makes ROE the closest single accounting number to the return an equity investor actually earns over long periods. A company that reliably compounds book equity at 15% while retaining most of its earnings is creating value at roughly that rate. It is also the ratio that sets the ceiling on self-funded growth: a business that earns 15% on equity and pays out a third of its profit can grow its own balance sheet 10% a year without selling shares or adding leverage.
The catch is that ROE is not purely an operating measure. Borrow money, buy back stock, or write off an asset and ROE rises without anything improving in the business. A high ROE therefore needs a follow-up question, always the same one: is this coming from operating performance or from a shrinking denominator?
The formula, term by term
The numerator is income available to common shareholders: net income less dividends declared on preferred stock. That is not an analyst's invention — it is the same figure ASC 260 requires as the numerator of basic earnings per share, which is why this calculator and the basic EPS calculator agree on the top line.
The denominator is average common equity: opening plus closing total equity divided by two, less the carrying value of preferred stock. Both adjustments matter for the same reason. The preferred shareholders have a claim on part of the equity and receive their own dividend, so leaving preferred capital in the denominator while removing preferred dividends from the numerator understates the common return, and leaving both in measures a blended return that belongs to nobody in particular. Where a subsidiary is consolidated, noncontrolling interests are excluded on the same logic.
Why the denominator is an average. Net income accumulates across the period; equity is a balance on one date. Any company that retained earnings during the year ends with more equity than it had available to work with, so dividing by the closing balance flatters nothing and understates the return. The default figures show the size of the effect: 28.50% on the average, 25.91% on the closing balance.
What negative equity does. If accumulated losses or buybacks have pushed book equity below zero, ROE stops meaning anything. Worse, a loss divided by negative equity produces a positive percentage that looks like a healthy return. This calculator returns "undefined" instead, and you should reach for return on invested capital in that situation.
Worked example: $120,000 of profit over $400,000 of common equity
A company earned $120,000 of net income. It has preferred stock carried at $100,000 paying $6,000 a year. Total equity opened at $460,000 and closed at $540,000, and $34,200 of common dividends were declared.
- Average total equity. ($460,000 + $540,000) ÷ 2 = $500,000.
- Strip out the preferred. $500,000 − $100,000 = $400,000 of average common equity.
- Income available to common. $120,000 − $6,000 = $114,000.
- Return on common equity. $114,000 ÷ $400,000 = 0.285 = 28.50%.
- Compare with the total-equity version. $120,000 ÷ $500,000 = 24.00%. The preferred stack is cheap relative to what the assets earn, so the common shareholder does better than the blended figure suggests.
- Payout ratio. $34,200 ÷ $114,000 = 30.00%, so retention is 70%.
- Sustainable growth rate. 28.50% × 0.70 = 19.95%. Book equity can compound at almost 20% a year with no new shares and no change in leverage.
Sanity-check that last figure against reality before you rely on it. Growing equity at 19.95% a year requires the business to find profitable use for the $79,800 it retains in year one ($114,000 − $34,200), then more each year after. The sustainable growth rate is an arithmetic ceiling on self-funding, not evidence that the opportunities exist.
How to read an ROE
Compare ROE against the cost of equity, not against a fixed target. If a company earns 14% on equity while shareholders require 9% for the risk they are taking, each retained dollar adds value; if it earns 6% against the same 9%, retaining earnings destroys value and the cash belongs back with the owners. That comparison, not the level of ROE, is the decision.
Then ask where the ROE came from, because the three-step DuPont identity gives only three possible sources: margin, asset turnover and leverage. Two identical companies can show 18% ROE with one earning it from a 12% margin at low leverage and the other from a 3% margin at four times leverage. The first is durable and the second is a bet on stable conditions. The DuPont analysis calculator separates them, and the debt-to-equity ratio calculator sizes the leverage component.
Long-standing rules of thumb, not statistics: bank analysts have traditionally looked for about 1% return on assets, which at the ten-to-twelve-times leverage a bank runs is a 10% to 12% ROE; a broad industrial business earning consistently above 15% is unusual and worth understanding; anything above 40% usually signals a small or artificially reduced equity base rather than exceptional operations.
Two red flags. While profit is positive, sustained buybacks shrink book equity and ROE climbs mechanically each year even with flat income — check whether income in dollars actually grew. (In a loss year the same shrunken equity base makes the negative ROE look worse, not better, which is why the ratio alone never settles the question.) And a large impairment cuts equity permanently, leaving every future year's ROE flattered by a past mistake.
How leverage turns return on assets into return on equity
| ROA | 1.0× | 1.5× | 2.0× | 3.0× | 5.0× | 10.0× |
|---|---|---|---|---|---|---|
| 2% | 2.0 | 3.0 | 4.0 | 6.0 | 10.0 | 20.0 |
| 4% | 4.0 | 6.0 | 8.0 | 12.0 | 20.0 | 40.0 |
| 6% | 6.0 | 9.0 | 12.0 | 18.0 | 30.0 | 60.0 |
| 8% | 8.0 | 12.0 | 16.0 | 24.0 | 40.0 | 80.0 |
| 10% | 10.0 | 15.0 | 20.0 | 30.0 | 50.0 | 100.0 |
The 10× column is roughly where a commercial bank operates, which is how 1% on assets becomes a low-double-digit return on equity. The identity holds exactly when ROA and the multiplier both use average balances.
Sustainable growth rate for each ROE and payout combination
| ROE | 0% payout | 25% | 40% | 60% | 100% |
|---|---|---|---|---|---|
| 8% | 8.00 | 6.00 | 4.80 | 3.20 | 0.00 |
| 12% | 12.00 | 9.00 | 7.20 | 4.80 | 0.00 |
| 16% | 16.00 | 12.00 | 9.60 | 6.40 | 0.00 |
| 20% | 20.00 | 15.00 | 12.00 | 8.00 | 0.00 |
| 25% | 25.00 | 18.75 | 15.00 | 10.00 | 0.00 |
Grow revenue faster than the figure in your cell and you must issue equity, borrow more, or improve the underlying ratios. Grow slower and cash piles up.
Mistakes that make an ROE misleading
- Using closing equity for a company that retained earnings. The denominator then includes profit the business never had available to work with, understating the return.
- Leaving preferred capital in the denominator. If you deduct preferred dividends from the numerator, deduct preferred stock from the denominator too, or the ratio is internally inconsistent.
- Reading a high ROE as operating excellence. In a profitable company, leverage, buybacks and past write-offs all raise it without anything improving in the business. Check return on assets and return on invested capital before you conclude anything.
- Computing ROE with negative book equity. A loss over negative equity yields a positive percentage that means nothing. Report it as undefined.
- Mixing consolidated equity with parent-only income. Exclude noncontrolling interests from both halves, or include them in both.
- Treating the sustainable growth rate as a forecast. It is a constraint that assumes constant margins, turnover, leverage and payout, and no share issuance. Real companies breach all five assumptions.
- Comparing across capital structures. A utility at four times leverage and a software firm at one is not a fair ROE comparison. Compare inside an industry.
Where these figures come from in the filings
ROE is not defined by US GAAP or IFRS, but its parts are. SEC Regulation S-X, Rule 5-02 prescribes the equity captions on the balance sheet, including preferred stock, common stock, additional paid-in capital, retained earnings and accumulated other comprehensive income; their sum is the total equity figure to enter. ASC 260 defines income available to common shareholders, the numerator here, and the statement of changes in shareholders' equity reconciles the opening and closing balances line by line — use it to see whether equity moved because of profit, dividends, buybacks or other comprehensive income.
One practical note: dividends belong in this calculation when declared, not when paid, which is also the ASC 260 convention for the EPS numerator. A dividend declared in December and paid in January reduces this year's retained earnings and this year's payout ratio.
ROE, ROIC and residual income
Use ROE when the question is what the owner earned, and something else when the question is how good the business is. Return on assets removes leverage from the picture by measuring profit against everything the company controls; ROE equals ROA multiplied by the equity multiplier, so the gap between them is exactly the contribution of borrowing. Return on invested capital goes further and measures operating profit against operating capital, which is the version to compare against a weighted average cost of capital.
Residual income takes the last step: subtract a charge for equity capital from net income and what remains is economic profit. A company with a 12% ROE and an 11% cost of equity is barely covering its capital charge, even though 12% sounds respectable. That framing is why analysts pair ROE with the sustainable growth rate calculator — growth is only worth funding when the return on the funded capital exceeds its cost.
For a quick diagnosis of a moving ROE, decompose it before you explain it. If net margin held and asset turnover fell, you have an asset-efficiency problem. If both held and ROE still rose, you added leverage. The identity leaves nowhere else for the change to come from.
Key terms
- Book equity
- Total assets less total liabilities: contributed capital plus retained earnings plus accumulated other comprehensive income, less treasury stock.
- Income available to common
- Net income less preferred dividends declared. The ASC 260 numerator for basic EPS and for return on common equity.
- Average common equity
- Opening plus closing total equity divided by two, less preferred capital. Averaging four or five quarter-end balances is better where the data exists.
- Payout ratio
- Common dividends declared divided by income available to common. Its complement is the retention ratio.
- Sustainable growth rate
- ROE multiplied by the retention ratio. The fastest equity, and therefore assets and sales, can grow at constant ratios with no share issuance.
- Equity multiplier
- Average total assets divided by average equity. The leverage term that separates ROE from ROA.