Real vs. Nominal Cash Flow
Executive Summary
Key Takeaways
- ✓ Real cash flow is expressed in constant, inflation-adjusted purchasing power; nominal cash flow includes the effect of expected inflation.
- ✓ The discount rate basis must match the cash flow basis — nominal cash flows require a nominal discount rate, and real cash flows require a real discount rate.
- ✓ Mixing bases, typically discounting nominal cash flows at a real rate, understates the discount rate relative to the cash flow and overstates value.
- ✓ The approximate relationship between the two rate bases is given by the Fisher equation: (1 + Nominal Rate) = (1 + Real Rate) x (1 + Expected Inflation).
- ✓ Most corporate DCF valuations are built on a nominal basis throughout, since revenue and cost forecasts are typically produced in nominal, current-currency terms.
Definition¶
Real cash flow is cash flow expressed in constant, inflation-adjusted purchasing-power terms — the effect of expected future inflation is stripped out. Nominal cash flow includes that inflation effect and reflects the actual currency amounts a business expects to receive or pay in each future period. Both are legitimate bases for a DCF valuation, but the discount rate used must be built on the same basis as the cash flow it discounts.
The Matching Principle¶
A nominal discount rate embeds a market expectation of future inflation, since it is typically derived from observable nominal market inputs such as the risk-free rate on government bonds and the observed cost of debt. Applying that nominal rate to real (inflation-stripped) cash flows would discount too heavily, understating value, because the rate compensates for inflation that the cash flow forecast does not actually include. Conversely, discounting nominal cash flows at a real discount rate understates the discount rate relative to the cash flow's embedded inflation growth, overstating value. The two bases must match throughout the model — cash flows, discount rate, and terminal growth rate all real, or all nominal.
The Fisher Equation¶
The approximate relationship between the two rate bases is given by the Fisher equation:
(1 + Nominal Rate) = (1 + Real Rate) x (1 + Expected Inflation)
A simplified linear approximation, Nominal Rate is approximately Real Rate plus Expected Inflation, is commonly used for small inflation figures but becomes progressively less accurate as inflation rises, since it omits the cross-product term.
Practice in Corporate DCF Valuation¶
Most corporate DCF valuations are built entirely on a nominal basis. Revenue, cost, and capital expenditure forecasts are typically produced in nominal, current-currency terms by operating management, and the observable market inputs used to build WACC — the risk-free rate and cost of debt — are themselves nominal rates. Real-basis DCFs are more common in specific inflation-linked contexts, such as regulated infrastructure assets with inflation-indexed revenue, or long-dated project finance analysis where inflation assumptions are made explicit and separately from the base forecast.
Audit Considerations¶
- Confirm the cash flow forecast basis (real or nominal) is explicitly stated and consistent throughout the model
- Confirm the discount rate's components — risk-free rate, cost of debt, and any embedded inflation assumption — are built on the same basis as the cash flow forecast
- Confirm the terminal growth rate assumption is consistent with the basis; a nominal terminal growth rate should not exceed long-run nominal GDP growth, while a real terminal growth rate should not exceed long-run real GDP growth
- Where a real-basis model is used, confirm the inflation assumption applied to convert between bases is disclosed and reasonable
Common Errors¶
| Error | Description | Risk |
|---|---|---|
| Mismatched cash flow and discount rate basis | Nominal cash flows discounted at a real rate, or vice versa | Materially overstates or understates value depending on the direction of the mismatch |
| Inconsistent terminal growth basis | A nominal terminal growth rate applied after a real-basis explicit forecast period, or the reverse | Produces an internally inconsistent terminal value |
| Undisclosed inflation assumption | A real-basis model with no stated inflation assumption used to reconcile against nominal market discount rate inputs | The reconciliation cannot be independently checked |
Continue Reading¶
Prerequisites¶
- Discounted Cash Flow (DCF) Valuation — the parent pillar
- WACC
Related Glossary¶
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Frequently Asked Questions
What is the difference between real and nominal cash flow?
Real cash flow is expressed in constant purchasing-power terms, with the effect of expected future inflation stripped out. Nominal cash flow includes that inflation effect and reflects the actual currency amounts a business expects to receive or pay in each future period.
Why does the real vs. nominal distinction matter in a DCF?
Because the discount rate must be built on the same basis as the cash flow it discounts. A nominal discount rate embeds an inflation expectation and must be applied to nominal cash flows; a real discount rate excludes inflation and must be applied to real cash flows. Mismatching the two bases produces a materially wrong valuation.
What happens if nominal cash flows are discounted at a real rate?
The discount rate is too low relative to the cash flow being discounted, since the real rate omits the inflation compensation embedded in the nominal cash flow growth. This understatement of the discount rate produces an overstated present value.
How do real and nominal discount rates relate to each other?
Approximately via the Fisher equation: (1 + Nominal Rate) = (1 + Real Rate) x (1 + Expected Inflation). A simplified approximation, Nominal Rate ≈ Real Rate + Expected Inflation, is commonly used but becomes less accurate at higher inflation levels.
Which basis is more common in practice?
Most corporate DCF valuations are built entirely on a nominal basis, since revenue, cost, and capital expenditure forecasts are typically produced in nominal, current-currency terms and the observable market discount rate inputs (risk-free rate, cost of debt) are themselves nominal. Real-basis DCFs are more common in inflation-linked contexts such as regulated infrastructure or long-dated project finance.
Related Articles
Discount Rate
The discount rate is the rate used to convert a future cash flow into its equivalent value today, reflecting both the time value of money and the risk associated with actually receiving that cash flow. In a discounted cash flow valuation, the discount rate is not a single, universal figure — it must match the cash flow being discounted. Unlevered free cash flow (FCFF), which is available to all capital providers, is discounted at the weighted average cost of capital (WACC), producing enterprise value. Levered free cash flow (FCFE), which is available only to equity holders after debt service, is discounted at the cost of equity, producing equity value directly. Selecting the wrong discount rate for a given cash flow is one of the most consequential and common errors in DCF valuation, since a mismatch corrupts both the theoretical basis and the resulting figure.
WACC (Weighted Average Cost of Capital)
WACC (Weighted Average Cost of Capital) is the rate of return that a company must earn on its existing assets to maintain the value of its equity and satisfy both its debt holders and equity investors. It is calculated as the weighted average of the after-tax cost of debt and the cost of equity, with the weights determined by the proportion of each in the total capital structure. WACC is used primarily as the discount rate in a discounted cash flow (DCF) valuation, where it converts projected free cash flows into present value. It is also used as a return hurdle: a project or investment is value-creating if its expected return exceeds the WACC.
Perpetuity Growth Rate
The perpetuity growth rate (also called the terminal growth rate or Gordon growth rate) is the assumed constant rate at which a business's free cash flow is expected to grow indefinitely beyond the explicit forecast period. It is the key assumption in the Gordon Growth Model method of calculating terminal value, and it must be strictly less than the discount rate for the perpetuity formula to produce a finite, meaningful value. Because no business can outgrow the broader economy forever, the perpetuity growth rate is conventionally capped at or near the long-run expected growth rate of GDP or inflation in the business's operating geography.
Free Cash Flow (FCF)
Free cash flow (FCF) is the cash a business generates from its operations that remains available after funding the capital expenditure needed to maintain or grow its operating assets. Unlike accounting profit, free cash flow strips out non-cash items (depreciation, amortization) and adjusts for the actual cash effects of working capital movements and capital spending, making it the relevant input for a discounted cash flow valuation. Free cash flow is expressed on one of two bases: unlevered free cash flow (FCFF), the cash available to all capital providers before financing effects, or levered free cash flow (FCFE), the cash available to equity holders after debt service. The choice of basis determines both the appropriate discount rate and what the resulting present value represents.