Efn (External Funding Needed) Calculator
Growth eats cash. Every extra dollar of sales needs assets behind it: inventory, receivables, equipment. Some of that funding arrives on its own, from suppliers who extend credit and from profits you keep in the business. The rest has to be raised from lenders or investors. External funding needed, or EFN, is the size of that gap for a growth plan you have not funded yet.
This calculator runs the textbook percentage-of-sales EFN formula, the same formula taught as AFN (additional funds needed) in corporate finance courses, plus three companion methods. Enter current sales, growth, assets, spontaneous liabilities, margin, retention and equity. It returns the funding gap, a sustainable growth rate check, and plain recommendations scaled to the size of the gap.
Quick Answer
For a company with $500,000 of sales growing 20%, $400,000 of assets, spontaneous liabilities at 40%, a 10% net margin and 60% retention, external funding needed is $4,000. Growth requires $80,000 of new assets; supplier credit covers $40,000 and retained profits cover $36,000, leaving $4,000 to raise. The sustainable growth rate on these figures is 12.00%, so the 20% plan grows faster than internal funding alone can support.
Key takeaways
- EFN is a gap, not a loan amount: it is what is left after spontaneous credit and retained profits have funded as much growth as they can.
- A negative result is good news. The tool shows it as $0 in the headline and lists the leftover as a funding surplus in the detail table.
- The Balance Sheet Approach builds the projected balance sheet line by line and takes EFN as the plug, so it cross-checks the Percentage of Sales result. Advanced Pro Forma runs the same standard pro forma projection, with no buffer added.
- The margin field does not work alone. Internal funding is credited only when net income is entered, so always fill in both.
- Quick Answer
- How to use the EFN calculator
- The EFN formula, exactly as this tool codes it
- Worked example: a $4,000 gap on 20% growth
- The four methods, and how each one works
- Reading the gap and closing it without new equity
- What competing calculators miss
- Frequently asked questions
- Add This Calculator to Your Website
- References
How to use the EFN calculator
Start with the Percentage of Sales method unless you have a reason to switch. It is the standard textbook approach and the right default for coursework and for a first-pass funding plan.
- Sales and growth: enter last period's sales and the growth rate you are planning for. The tool builds projected sales and the sales increase from these two numbers.
- Net income and retention: enter current net income and the share of profit you keep. Retention is 100% minus the payout you make through dividends, so a 40% payout means entering 60 here.
- Assets: enter total assets. The tool derives the asset-to-sales ratio itself, so you never have to pre-compute A/S.
- Spontaneous liabilities: enter L/S as a percent: your payables and accruals balance divided by current sales, times 100. The tool applies that percent to the sales increase, which is exactly the (L/S) term in the formula.
- Margin and equity: the margin auto-fills from net income over sales and can be overridden for scenarios. Equity is used only for the ROE and sustainable growth check.
- Read the detail table, not just the headline: it shows required assets, internal funding, spontaneous financing, the sustainable growth rate and EFN as a percent of projected sales, followed by recommendations sized to the gap.
The EFN formula, exactly as this tool codes it
The formula is the percent-of-sales EFN equation from corporate finance textbooks: EFN = (A/S) × ΔS − (L/S) × ΔS − (PM × S1 × (1 − d)), where retention (1 − d) is what is left after the dividend payout ratio d. The Executive Financial Management training module on the EFN formula sets out the same three terms, and the Pearson chapter on forecasting with the percent of sales method explains why balance sheet items are scaled to sales in the first place.
Sales increase (ΔS) = S1 − Current sales
Required asset increase = (Total assets ÷ Current sales) × ΔS
Spontaneous financing = Spontaneous % × ΔS
Internal funding = S1 × Profit margin × Retention ratio
EFN = Required asset increase − Spontaneous financing − Internal funding
Three assumptions sit inside that arithmetic, and they matter more than the arithmetic itself. First, assets are assumed to scale in proportion to sales, which is the full-capacity assumption: if your plant or warehouse has spare capacity, the real asset increase will be smaller and EFN is overstated. Second, the margin and retention ratio are held constant into next period. Third, assets that arrive in lumpy steps, such as a whole new machine rather than a smooth fraction of one, break the proportionality, so treat the result as a planning estimate and re-run it with the actual purchase price when a big step purchase is coming.
Worked example: a $4,000 gap on 20% growth
A company has $500,000 in current sales, projects 20% growth, holds $400,000 in assets, carries spontaneous liabilities equal to 40% of the sales increase, earns a 10% net margin, retains 60% of profits, and has $250,000 of equity. These are the values pre-filled in the calculator, and every number below is the tool's own output for them.
| Detail line (as the tool reports it) | Value |
|---|---|
| Current sales | $500,000 |
| Projected sales | $600,000 |
| Sales increase (20%) | $100,000 |
| Asset-to-sales ratio | 0.800 |
| Required asset increase | $80,000 |
| Internal funding (retained) | $36,000 |
| Spontaneous financing | $40,000 |
| Sustainable growth rate | 12.00% |
| EFN as % of projected sales | 0.67% |
| External funding needed | $4,000 |
Where the $80,000 of required new assets gets funded from:
Supplier credit does half the work here, which is typical for trading businesses with generous payable terms. It is also the fragile half: if suppliers tighten terms at the same moment you accelerate growth, the spontaneous line shrinks and the gap lands on your credit line instead. Watching comparable sales growth against plan during the year tells you early whether the projected side of this calculation is holding up.
The four methods, and how each one works
All four methods start from the same inputs. Percentage of Sales applies the textbook equation directly, Balance Sheet builds the projected statement and takes EFN as the plug, and Advanced Pro Forma runs the standard pro forma projection. Sustainable Growth is the only method that changes the answer, and only through its zero rule.
| Method | What the code actually does | EFN on the worked example |
|---|---|---|
| Percentage of Sales | The standard textbook formula, unchanged. | $4,000 |
| Balance Sheet Approach | Builds the pro forma balance sheet line by line: total assets and spontaneous liabilities are scaled to projected sales, non-spontaneous liabilities are held constant, retained earnings are rolled forward into equity, and EFN is the plug that makes projected assets equal projected liabilities plus equity. | $4,000 |
| Sustainable Growth Model | Computes the standard gap only when planned growth exceeds the sustainable growth rate. At or below that rate it reports $0 by construction, even if the plain formula would show a small gap. | $4,000 (growth 20% is above the 12% rate) |
| Advanced Pro Forma | The standard pro forma projection: the textbook formula applied to projected sales, with no buffer or cushion added. | $4,000 |
The sustainable growth rate behind the third method is worth understanding on its own. The Corporate Finance Institute's sustainable growth rate guide defines it the way this tool computes it: retention rate multiplied by return on equity, the fastest growth a company can sustain without new equity while holding its financing mix. On the worked example that is 20.00% ROE × 60% retention = 12.00%, against a planned 20%, which is why the tool flags the plan as growing beyond internal capacity. The equity figure you enter is the base for that ROE, so the rate follows the beginning-equity convention used in the textbook derivation.
Reading the gap and closing it without new equity
Size the gap against current sales before choosing a funding source. The calculator's recommendations follow these bands, and the verdict badge on the result uses the same cut-offs.
| EFN vs current sales | Reading | Typical response |
|---|---|---|
| Zero or negative: surplus | The plan funds itself. | Accelerate growth, repay debt, or raise the payout. |
| Under 10%: moderate | Routine growth funding. | Short-term credit facility or a small equity injection. |
| 10% to 25%: significant | Growth is outpacing internal generation. | A planned mix of debt and equity, arranged before the year starts. |
| Over 25%: high | The plan needs outside capital at scale. | Staged growth, a strategic partner, or a major equity raise. |
Before borrowing the full gap, test the four internal levers, because each one moves EFN directly. Raising the margin adds internal funding on every projected sales dollar. Raising retention does the same, at the cost of a lower payout. Improving asset turnover lowers A/S, so each growth dollar needs fewer assets behind it; tightening the days working capital cycle is the usual way that shows up in practice, since receivables and inventory are the assets that swell first. Slowing the growth target is the fourth lever, and the honest one: a plan at the sustainable rate needs no external equity at all. Whichever mix you choose, sanity-check the result against the business's ability to service new debt, which is what a cash flow adequacy ratio measures once the plan is running.
What competing calculators miss
Most AFN tools online ask you to do the hard part yourself. They want the change in assets, the change in liabilities and the change in retained earnings typed in as finished numbers, which means you have already solved the problem before the calculator starts. Others take the balance-sheet plug route with projected totals and no growth, margin or retention inputs at all, so there is no way to ask what happens if growth is 15% instead of 20%.
- Pre-computed changes: step-by-step AFN tools that take ΔAssets, ΔLiabilities and ΔRetained Earnings as inputs never derive A/S, L/S or projected retained earnings from your statements. This tool derives all three, and shows the ratios it derived.
- A misstated formula: at least one AFN calculator states its formula with the asset and liability ratios multiplied by projected sales rather than by the increase in sales, which overstates the asset need whenever it is followed literally. Here the ratios multiply ΔS, as the textbook formula requires.
- No sustainable growth cross-check: a gap number alone cannot tell you whether the growth target itself is realistic. This tool reports the sustainable growth rate next to every EFN and flags plans running more than 5 points above or below it.
- Negative results left unexplained: several tools print a negative number with no interpretation. Here a negative gap is labelled a funding surplus, quantified in the detail table, and the headline reads $0 so the surplus is never mistaken for a debt requirement.
Frequently asked questions
It means the growth plan funds itself. Internal funding from retained profits plus spontaneous financing is larger than the asset increase the growth requires, so the headline EFN shows $0 and the detail table lists the leftover as a funding surplus. In the percentage-of-sales method at 10% growth on the worked example, the surplus is $13,000, which can support faster growth, debt repayment or higher dividends.
Yes. Textbooks and courses use both names for the same funding gap: required asset increase minus spontaneous financing minus retained earnings. Ross, Westerfield and Jordan call it external financing needed (EFN); other texts call it additional funds needed (AFN). The arithmetic is identical.
The retention ratio is the share of net income the business keeps instead of paying out as dividends. It equals 1 minus the dividend payout ratio, so a company that pays out 40% of profits retains 60%. You can read both figures from the income statement and the statement of retained earnings: retention is the addition to retained earnings divided by net income.
Accounts payable and accrued expenses, such as wages and taxes payable, because they rise automatically as sales and production rise. Notes payable, bank loans and long-term debt are not spontaneous: they only change when management arranges new borrowing, so the formula leaves them out and treats them as part of the external funding decision instead.
That is how this mode is built. It compares your planned growth with the sustainable growth rate (ROE multiplied by the retention ratio). If planned growth is at or below that rate, the mode reports $0 on the grounds that the plan is self-fundable, even if the plain formula would show a small gap. Run the percentage-of-sales method alongside it when you need the unadjusted gap.
No. The Advanced Pro Forma method runs the standard pro forma projection: the textbook EFN formula applied to projected sales, with no buffer or cushion added. On the worked example it returns the same $4,000 as the percentage-of-sales method.
Yes, by a different route. Instead of applying the EFN equation directly, it builds the projected balance sheet: total assets and spontaneous liabilities are scaled to projected sales, non-spontaneous liabilities are held constant, and retained earnings are rolled forward into projected equity. EFN is then reported as the plug, projected total assets minus projected total liabilities and equity. Because both methods project the same statements, the Balance Sheet result agrees with the percentage-of-sales result for the same inputs, so the two methods cross-check each other.
Internal funding in this tool is switched on by the net income figure: the code only credits retained profits when net income is entered, using the margin (typed or auto-filled) to project them. A margin typed on its own therefore produces $0 of internal funding and a larger EFN. Enter current net income as well and the margin will auto-fill from it.
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References
- Executive Financial Management (ExInFM). The EFN Formula, Fundamentals of Corporate Finance. Accessed October 21, 2026.
- Pearson Education. Forecasting Financial Statements: The Percent of Sales Method. Accessed October 21, 2026.
- Corporate Finance Institute. Sustainable Growth Rate. Accessed October 21, 2026.
- Corporate Finance Institute. Internal Growth Rate (IGR). Accessed October 21, 2026.
- O'Reilly Media, Financial Forecasting and Decision Making. Appendix A: The Basic Forecasting Model. Accessed October 21, 2026.