Sustainable growth rate = ROE × retention ratio; it is the maximum rate a firm can grow using only retained earnings without external financing. Higher payout ratios reduce growth but may signal confidence or target mature companies.
Calculate sustainable growth for several companies with different payout policies. Observe how retention and ROE interact to determine dividend policy feasibility.
From stock valuation fundamentals, you learned that a firm's value depends on its future cash flows, which depend in part on how fast it can grow. But growth does not come for free — it requires capital. A firm can finance growth by retaining earnings, issuing new equity, or borrowing. This topic asks a foundational question: how fast can a firm grow using only the profits it generates internally, without changing its capital structure or issuing new shares?
The answer is the sustainable growth rate (SGR) = ROE × b, where ROE (return on equity) measures the rate at which the firm converts its equity base into new earnings, and b is the retention ratio (the fraction of earnings kept rather than paid out as dividends). The logic is direct: if a firm earns 20% on equity and retains 60% of those earnings, it adds 12% to its equity base from internal sources each year. If assets, revenues, and liabilities all grow proportionally to equity, the firm can sustain 12% growth without external financing. Growth beyond this rate requires issuing new equity or taking on additional debt — either of which changes the firm's financial structure.
Since retention ratio = 1 − payout ratio, SGR = ROE × (1 − payout ratio). This reveals the fundamental trade-off in dividend policy: every dollar paid as a dividend is a dollar not reinvested to fund growth. A mature firm with few high-return investment opportunities should pay high dividends — retaining earnings to reinvest at mediocre returns destroys value compared to distributing them. A high-growth firm with abundant opportunities earning returns well above its cost of capital should retain most earnings rather than paying dividends and then reissuing equity at a cost. The payout ratio is not just a distribution decision; it implicitly determines how much growth the firm can self-finance.
The SGR formula also embeds DuPont decomposition insights. ROE = profit margin × asset turnover × financial leverage (Net Income/Sales × Sales/Assets × Assets/Equity). A firm can improve its SGR by improving operating margins, using assets more efficiently, or taking on more leverage — though leverage raises financial risk and is not free. This makes SGR useful as a diagnostic: two firms with identical SGRs may achieve them through very different means, one through operational excellence and the other through high leverage, with very different risk profiles and sustainability.
Crucially, SGR assumes the firm maintains its current financial ratios. If actual growth exceeds the SGR, something must give: the firm must issue new equity, increase its debt ratio, or accept that some ratios will change. Firms that consistently grow faster than their SGR without raising equity are implicitly accumulating debt — their leverage is rising with each passing year. If this trajectory is not corrected, it can become financially unsustainable. SGR is therefore a valuable benchmark not just for equity valuation but for credit analysis: a firm whose planned growth far exceeds its SGR deserves scrutiny about how that gap will be financed.