Sustainable growth rate: how fast can a company afford to grow?
Not every growth rate can be financed. The sustainable growth rate shows how fast a company can grow without new equity; a worked example.
The sustainable growth rate is the fastest a company can grow without raising new equity and without changing its debt-to-equity balance. Every profitable company assumes it can grow, but growth is limited not just by profit but by how the assets that growth absorbs will be financed. More sales mean more receivables, more inventory and often more investment. In this article I explain how the sustainable growth rate is calculated, which levers move it, and what options management has when the growth target exceeds it, with a worked example.
The formula and its logic
In its most common form the sustainable growth rate is:
Sustainable growth rate = Return on equity (on opening equity) × Retention ratio
The retention ratio is the share of net profit kept in the business rather than paid out (1 − payout ratio). The logic is simple: if the company raises no new equity, equity grows only by retained profit. If the debt-to-equity ratio is held constant, debt can grow at the same rate; so if total assets and the asset-to-sales relationship are stable, sales can grow at that rate too.
Return on equity itself can be split into three components: net profit margin, asset turnover and financial leverage. This breakdown (DuPont analysis) reveals four levers that drive the sustainable growth rate:
- Net profit margin
- Asset turnover (sales / total assets)
- Financial leverage (total assets / equity)
- Retention ratio
I cover DuPont analysis in detail in ROE and DuPont analysis.
A hypothetical example
The company below is hypothetical. Figures are in TRY million.
| Item | Value |
|---|---|
| Annual sales | 100.0 |
| Net profit margin | 5% |
| Net profit | 5.0 |
| Total assets (80% of sales) | 80.0 |
| Equity (40% of assets) | 32.0 |
| Debt | 48.0 |
| Debt / equity | 1.5 |
| Payout ratio | 40% |
The calculation:
- Return on equity = 5.0 / 32.0 = 15.625% (also 5% margin × 1.25 asset turnover × 2.5 leverage)
- Retention ratio = 1 − 0.40 = 0.60
- Sustainable growth rate = 15.625% × 0.60 = 9.375%
To check it: the company retains TRY 3.0 million of its TRY 5.0 million profit. Equity grows from 32.0 to 35.0, or 9.375%. If debt-to-equity stays at 1.5, debt can rise from 48.0 to 52.5, taking total assets to 87.5. With assets at 80% of sales, those assets support TRY 109.375 million of sales — sales have also grown 9.375%.
When the growth target exceeds the sustainable rate
Suppose management targets 20% growth for this company. With everything else unchanged:
| TRY million | Start | After 20% growth |
|---|---|---|
| Sales | 100.0 | 120.0 |
| Net profit (5%) | 5.0 | 6.0 |
| Retained (60%) | — | 3.6 |
| Total assets (80% of sales) | 80.0 | 96.0 |
| Equity | 32.0 | 35.6 |
| Debt (balancing figure) | 48.0 | 60.4 |
| Debt / equity | 1.50 | 1.70 |
Twenty per cent growth is possible, but without new equity the debt-to-equity ratio rises from 1.50 to about 1.70. That may or may not stay within what the bank will accept, and it may trip a covenant in the loan agreement. What matters is seeing this consequence when the growth decision is taken. I discuss managing loan covenants in managing financial covenants.
The four levers and their effect
Changing each lever on its own in the same example moves the sustainable growth rate as follows:
| Change | New ROE | Sustainable growth |
|---|---|---|
| Starting position | 15.6% | 9.4% |
| Payout ratio cut from 40% to 20% | 15.6% | 12.5% |
| Net margin up from 5% to 6% | 18.75% | 11.25% |
| Assets/sales down from 80% to 70% (higher turnover) | 17.9% | 10.7% |
The table shows that funding growth is not only about finding new loans or capital. Raising asset turnover — making the same sales with fewer receivables and less inventory — lifts the sustainable growth rate directly. I cover shortening collection periods in how to reduce DSO and inventory management in inventory turnover and slow-moving stock.
The formula’s assumptions and limits
The sustainable growth rate is a powerful shortcut, but its assumptions need to be understood:
- Ratios are held constant: margin, asset turnover, leverage and payout are assumed not to change. In reality margins often change with scale during growth, and asset turnover falls in investment-heavy periods.
- Assets grow in proportion to sales: a company with spare capacity can grow for a while without investing; one running at capacity faces a sudden, large investment need.
- Accounting profit is not cash: the formula works with profit. If profit converts poorly into cash (for example because receivables are piling up), real funding capacity is lower than the formula suggests.
- Care in high-inflation periods: revenue growth driven by price increases also ties up working capital. Nominal and real growth should be assessed separately.
So the sustainable growth rate should be used as a warning indicator, with the real decision based on a financial model that includes cash flow. I explained why profit does not always turn into cash in why profitable companies run out of cash.
Practical use for management
A practical way to use the sustainable growth rate in management meetings is to put three numbers side by side each year in the budget round:
- The target growth rate
- The sustainable growth rate at current ratios
- The funding needed to close the gap (more debt, more equity or working capital improvement)
If the gap is large there are three routes: lower the growth target, improve the ratios (margin, turnover, payout policy) or find outside funding. Which route to take is as much a strategic choice as a financial one. I discussed how dividend policy in family businesses affects that choice in the CFO’s role in a family business.
Conclusion
The sustainable growth rate is a quick test of whether growth targets are realistic in funding terms. If the target exceeds it, the gap has to be closed with debt, equity or more efficient working capital. I explained how to build this calculation into the strategic plan in linking the strategic plan to the financial plan. You can read about my growth and funding planning work on the financial management page.