Pro Forma Financial Statements: Percent-of-Sales Method, EFN & Growth Rate Formulas

When a company plans to grow, one question dominates every boardroom discussion: how much new financing will we need? Pro forma financial statements answer that question by translating a sales growth forecast into projected income statements and balance sheets, revealing the gap between what the business generates internally and what it must raise from outside investors. Whether you are evaluating a capital budgeting decision, preparing a loan application, or studying for a finance exam, mastering pro forma analysis is essential.

What Are Pro Forma Financial Statements?

Pro forma financial statements are forward-looking projections of a company’s income statement and balance sheet based on specific assumptions about future sales growth, cost ratios, and financing decisions. Unlike historical ratio analysis or DuPont decomposition, which examine what already happened, pro forma analysis looks ahead to estimate what will happen under a given growth scenario.

Companies use pro forma statements for budgeting, strategic planning, communicating with investors and lenders, and evaluating whether a growth plan is financially feasible. The sales forecast is the single most important assumption in the entire model — every other line item flows from it.

A complete financial model also projects the cash flow statement and free cash flow, which feed into DCF valuation. This article focuses on the income statement, balance sheet, and the financing gap that connects them — the core of pro forma analysis as presented in Berk, DeMarzo & Harford Chapter 18.

The Percent-of-Sales Method

The most widely used approach to building pro forma statements is the percent-of-sales method. It assumes that many income statement and balance sheet items maintain a constant ratio to sales as the company grows.

Items that typically scale with sales include cost of goods sold, selling and administrative expenses, accounts receivable, inventory, minimum operating cash, and accounts payable. These items are operationally linked to revenue — when sales rise, they rise proportionally.

Items that do not scale with sales include long-term debt, stockholders’ equity, interest expense, and dividends. These reflect active financing and payout decisions rather than operating relationships. In the percent-of-sales framework, they are marked “NM” (Not Meaningful) and forecast separately.

Building a Pro Forma Income Statement

Consider KMS Designs, a company with $74,889 thousand in sales that forecasts 18% growth next year. Using historical cost ratios, we project each line item:

Building a Pro Forma Balance Sheet

The balance sheet follows the same logic: scale operating items with sales, hold financing items constant, and identify the gap.

The External Financing Needed (EFN) Formula

Rather than building an entire balance sheet, you can estimate the financing gap directly with the EFN formula:

Where:

• A/S — total assets as a fraction of sales (asset intensity)
• L/S — spontaneous liabilities (AP, accruals) as a fraction of sales
• ΔS — change in sales (S₁ − S₀)
• PM — net profit margin (net income ÷ sales)
• S₁ — projected sales
• d — dividend payout ratio

Sustainable Growth Rate vs Internal Growth Rate

Two benchmark growth rates help managers understand how fast their company can grow without changing its financing mix. Both formulas use beginning-of-period assets and equity (the Berk convention).

Because ROE exceeds ROA whenever a firm has debt, the sustainable growth rate is always higher than the internal growth rate. The SGR allows new borrowing — just enough to maintain the existing debt-to-equity ratio — while the IGR relies on retained earnings alone.

Three Growth Zones

These two benchmarks create three distinct financing zones:

DuPont analysis reveals what drives the ROE that powers the sustainable growth rate — breaking ROE into profit margin, asset turnover, and financial leverage helps identify which levers management can pull to raise the SGR.

Pro Forma Financial Statements Example

Returning to KMS Designs, we can now put the full picture together. KMS’s own growth benchmarks are:

• ROA = $6,941 / $90,616 = 7.66%, ROE = $6,941 / $74,134 = 9.36%, Retention = 0.70
• IGR = 7.66% × 0.70 = 5.4%
• SGR = 9.36% × 0.70 = 6.6%
• Forecasted growth: 18% — well above both benchmarks

Because KMS is growing at nearly three times its SGR, it needs $8,396 thousand in external financing — management must decide how to raise it and whether the growth plan creates enough value to justify the capital raise.

Real-World Context: Procter & Gamble

Procter & Gamble provides a contrasting example. With roughly $67 billion in sales (FY 2019), P&G targeted about 5% organic revenue growth. Its ROE of approximately 27% (approximate; large buyback programs can mechanically inflate book ROE) and retention rate near 0.40 gave it a sustainable growth rate of roughly 11% — well above the planned 5% growth. P&G’s conservative growth relative to its SGR meant it generated excess cash, which it returned to shareholders through dividends and share buybacks rather than raising external capital.

How to Build a Pro Forma Model

Follow these eight steps to construct a pro forma model for any company:

1. Start with a realistic sales forecast — anchor to market size, market share, and pricing trends. The entire model depends on this assumption.
2. Identify which items scale with sales — calculate historical percentages for operating costs, working capital items (receivables, inventory, payables), and fixed assets.
3. Project the income statement top-down — apply cost ratios to forecasted sales, then calculate taxes and net income.
4. Project the balance sheet — scale operating items, hold debt and equity constant, and compute retained earnings (net income minus dividends).
5. Calculate the financing gap — subtract projected liabilities-plus-equity from projected assets to find net new financing (or use the EFN formula).
6. Decide how to fill the gap — choose between new debt, new equity, or a combination based on the company’s target capital structure.
7. Iterate if necessary — new debt changes interest expense, which changes net income, which changes retained earnings, which changes the gap. A second pass may be needed.
8. Benchmark against IGR and SGR — compare planned growth to the internal and sustainable growth rates to understand the financing implications and ensure the growth is value-creating.

Pro forma free cash flows feed directly into DCF valuation models, connecting the planning exercise to the company’s intrinsic value.

Common Mistakes

1. Assuming all balance sheet items scale with sales. Debt, equity, and dividends are financing decisions, not operating ratios. Only spontaneous items — accounts payable, accrued expenses, and operating assets — scale with sales. Applying the percent-of-sales method to interest-bearing debt produces a meaningless projection.

2. Confusing stockholders’ equity with retained earnings. New retained earnings equal net income minus dividends — they are added to total stockholders’ equity, which also includes par value of stock and additional paid-in capital. Projecting equity as simply “last year’s equity plus net income” overstates equity because it ignores dividends paid out.

3. Ignoring the iterative nature of pro forma modeling. Adding new debt increases interest expense, which reduces net income, which reduces retained earnings, which increases the financing gap further. A single pass may understate the true amount of external financing needed. In practice, two or three iterations are usually sufficient to converge.

4. Treating the sustainable growth rate as a ceiling. The SGR is a financing benchmark, not a speed limit. Growth above the SGR simply means external financing is required. If the growth involves positive-NPV projects, the company should pursue it and raise the necessary capital. Starbucks grew at 60% annually in the 1990s — three times its 20% SGR — while creating enormous shareholder value.

5. Using a single year’s ratios as permanent. Historical cost ratios can shift due to economies of scale, pricing changes, competitive pressures, or operational improvements. Fast-growing companies should use multi-year averages or trend-adjusted estimates rather than assuming last year’s percentages will hold indefinitely.

Limitations of Pro Forma Analysis

Linear scaling assumption. The percent-of-sales method assumes all operating items scale linearly, but real companies face step-function capacity constraints. A factory running at 90% capacity cannot serve 20% more demand without a major capital investment — costs jump in lumps, not smooth lines.

Static capital structure. The first-pass model holds interest expense constant, ignoring the feedback loop between new financing and increased interest costs. While iteration resolves this, many simple models skip this step and understate the true financing need.

Single-scenario output. A single pro forma projection provides one deterministic view of the future. Scenario analysis (best case, base case, worst case) and sensitivity analysis (how does EFN change if growth is 10% vs. 20%?) are essential complements.

Does not assess value creation. Pro forma statements forecast what will happen but not whether it creates shareholder value. Only NPV analysis — comparing the present value of future cash flows to the required investment — can determine whether planned growth is worth pursuing. See our guide to capital budgeting and free cash flow.