The price a stock trades at tells you what the market currently values it at. A discounted cash flow model tells you what it is arguably worth — given what its business will likely earn in the future, discounted back to today’s dollars.
DCF analysis is the closest thing finance has to a first-principles valuation: no peer multiples, no sector averages, just projected free cash flow, a discount rate, and arithmetic. Every investment bank, hedge fund, and equity research team uses some version of it. The mechanics are learnable in an afternoon. What takes years is understanding why the assumptions matter far more than the math.
The Core Idea: A Dollar Tomorrow Is Worth Less Than a Dollar Today
If someone offers you $100 today or $100 in five years, you take the money today. You could invest it and have more than $100 in five years. That opportunity cost is the foundation of all DCF analysis.
Formally, the present value of a future cash flow is:
PV = CF ÷ (1 + r)n
Where CF is the expected cash flow in year n, and r is the discount rate (how much you require in return for waiting and taking risk). The full DCF model sums this across every future year:
Enterprise Value = Σ [CFt ÷ (1+r)t] + Terminal Value ÷ (1+r)n
Because you cannot forecast cash flows to infinity, DCF models typically project 5–10 years explicitly, then estimate a terminal value (TV) — the lump-sum present value of all cash flows beyond the projection horizon.
The Terminal Value: Where Most of the Math Lives
The most common terminal value formula is the Gordon Growth Model (also called the perpetuity growth model):
TV = FCFn × (1 + g) ÷ (WACC − g)
Where FCFn is the final year’s free cash flow, g is the assumed terminal growth rate (typically 2–4%, anchored to long-run GDP growth), and WACC is the weighted average cost of capital — the blended required return for the company’s debt and equity investors.
A critical insight: terminal value typically accounts for 60–80% of a company’s total DCF valuation. That means the long-run growth and discount rate assumptions — inputs that are inherently uncertain — drive most of the result.
Worked Example: A Step-by-Step DCF
Suppose a hypothetical software company (call it TechCorp) currently generates $20 million in free cash flow and is expected to grow that at 15% per year for the next five years, then settle into a 3% terminal growth rate. Analysts set the discount rate (WACC) at 10%.
Step 1: Project free cash flows for Years 1–5.
Step 2: Discount each back to today at 10%.
Step 3: Calculate terminal value at end of Year 5.
Step 4: Discount terminal value back to today.
Step 5: Sum everything.
| Year | Projected FCF | PV Factor (10%) | Present Value |
|---|---|---|---|
| Year 1 | $23.0M | 0.909 | $20.9M |
| Year 2 | $26.5M | 0.826 | $21.9M |
| Year 3 | $30.4M | 0.751 | $22.8M |
| Year 4 | $35.0M | 0.683 | $23.9M |
| Year 5 | $40.2M | 0.621 | $25.0M |
| Terminal Value | $592M | 0.621 | $368M |
| Enterprise Value | $482M |
Notice the terminal value: $592M is the undiscounted perpetuity value of all cash flows beyond Year 5. Discounted back five years at 10%, it’s worth $368M today — fully 76% of the total $482M enterprise value. The five years of explicit forecasts together contribute only $114M, or 24%.
Chart: Where the $482M Actually Comes From
The Two Inputs That Decide Everything
WACC: The Discount Rate
WACC stands for Weighted Average Cost of Capital. It blends the cost of equity (what shareholders require) and the after-tax cost of debt (what lenders charge), weighted by the company’s capital structure:
WACC = (E/V × re) + (D/V × rd × (1 − Tax Rate))
Where E is equity market cap, D is total debt, V = E + D, re is cost of equity (often estimated via CAPM), and rd is pre-tax cost of debt. For a stable large-cap company, WACC typically runs 8–10%. For a high-growth startup, it might be 12–15%. A higher WACC shrinks the present value of every future cash flow.
Terminal Growth Rate (g)
The terminal growth rate is the assumed forever-rate at which free cash flows grow past the explicit forecast period. Most practitioners anchor it to nominal GDP growth — roughly 2–4% for developed economies. A terminal growth rate above the long-run GDP growth rate implies the company will eventually be larger than the entire economy, which is logically impossible. As a practical ceiling, analysts rarely use g above 4%.
How Sensitive Is the Output?
This is the most important thing to internalize: small changes in WACC and g produce enormous swings in enterprise value. The table below shows how TechCorp’s $482M base case changes across plausible input ranges.
The takeaway: a confident-looking DCF output is only as reliable as its most uncertain input. When you see an analyst target of “fair value: $X,” always ask what WACC and terminal growth assumptions are baked in. A model that uses WACC = 8% and g = 4% for an average company will produce a dramatically higher “fair value” than one using WACC = 12% and g = 2%.
Free Cash Flow vs. Earnings: Why FCF Is the Right Input
DCF models use free cash flow to the firm (FCFF), not net income or EPS. The reason: cash flow is harder to manipulate than reported earnings, and it reflects what the business actually generates after maintaining and growing its asset base.
The simplified formula is:
FCFF = Operating Income × (1 − Tax Rate) + D&A − Capital Expenditures − ΔWorking Capital
A company can report strong earnings while generating little or no free cash flow — for instance, if it requires heavy reinvestment (capex) to sustain growth, or if rising accounts receivable signals that customers aren’t paying on time. Free cash flow filters that out.
Where DCF Works — and Where It Breaks Down
DCF works well for:
- Mature, stable businesses with predictable cash flows (utilities, consumer staples, established software)
- Private company valuation, where no public market price exists
- Stress-testing an existing market valuation (“what growth rate does the current stock price imply?”)
DCF struggles with:
- Early-stage companies with no current free cash flow (the terminal value does all the work, amplifying uncertainty)
- Cyclical businesses (projecting “normal” FCF during a commodity downturn is notoriously difficult)
- Companies with optionality — platform businesses, drug pipelines, financial optionality — where standard DCF misses value embedded in future choices
- Highly capital-light or network-effect businesses, where growth doesn’t require proportional reinvestment and the right model is closer to a reverse DCF
The Reverse DCF: What Is the Market Pricing In?
One of the most practical applications of DCF isn’t building a model from scratch — it’s working backwards. Given the current stock price, market cap, and your estimate of WACC, you can solve for the implied growth rate. If the market is pricing in 25% annual FCF growth for 10 years at a 10% discount rate, ask yourself: how likely is that, and what has to go right? That question is often more useful than a standalone “fair value” estimate.
How to Find the Inputs in Real Filings
For a public company, you can build a rough DCF using publicly available data:
- Free cash flow: Cash flow statement → “Net cash from operating activities” minus “Capital expenditures.” Found in every 10-K filing on SEC EDGAR.
- Revenue and margin trends: Income statement, last 5 years.
- WACC components: Beta from financial data providers; risk-free rate from the U.S. Treasury yield curve; equity risk premium from the Damodaran annual dataset.
- Debt cost and tax rate: Notes to financial statements in the 10-K.
Related Concepts to Learn Next
- P/E ratio: A shortcut valuation that implicitly embeds growth and discount rate assumptions — useful for comparison, less rigorous than DCF.
- EV/EBITDA and EV/FCF multiples: Market-based comparables that analysts use to cross-check DCF outputs.
- CAPM: The standard model for estimating the cost of equity input to WACC.
- Free cash flow yield: FCF divided by market cap — a quick DCF-adjacent metric for identifying value.
Sources
- SEC EDGAR — 10-K filings (free cash flow data)
- U.S. Treasury — Daily yield curve (risk-free rate)
- Damodaran Online — Equity risk premium and country risk premium data
- CFA Institute — Discounted Cash Flow Valuation framework
Disclosure: This article was produced with AI assistance and reviewed before publication. It is for informational purposes only and is not investment advice.