DCF and WACC Explained: A Practical Valuation Guide

A plain-English guide to discounted cash flow (DCF) valuation: free cash flow, WACC, terminal value and why scenarios matter more than one number.

How a discounted cash flow model works, step by step: free cash flow, the WACC discount rate, terminal value and sensitivity analysis.

A discounted cash flow model, or DCF, estimates what a company is worth based on the cash it is expected to generate in the future, brought back to today's value with a rate that reflects risk. It sounds technical, but the core idea is simple. This guide explains each piece in plain English, shows the formulas in text, and points out where beginners most often go wrong.

Key takeaways

A company's value can be estimated as the sum of its future cash flows, discounted to the present.
WACC is the discount rate. It blends what shareholders and lenders expect to earn.
The terminal value often makes up a large share of the result, so it deserves extra caution.
A DCF gives a range, not a precise answer. Small changes in assumptions can move the result a lot.

1. The core idea: a dollar today is worth more than a dollar tomorrow

A dollar you have today can be invested and earn a return. A dollar promised in the future is uncertain: it might arrive late, arrive smaller, or not arrive at all. So future money has to be "discounted" to compare it fairly with money today.

Here is a round-number example, for illustration only. If you require a 10% return, a promise of $110 one year from now is worth about $100 today, because $100 invested at 10% would grow to $110. That process, applied to many years of a company's cash flows, is the heart of a DCF.

Remember that the result is an estimate, not a fact. It depends entirely on your assumptions about growth, profit margins and investment.

2. Free cash flow (FCF)

Accounting profit, or net income, can include items that are not real cash coming in or going out, such as depreciation. That is why a DCF works with free cash flow:

FCF = Cash flow from operations − Capital expenditures

Cash flow from operations is the cash the business generates from its day-to-day activities. Capital expenditures (capex) are what the company spends on equipment, buildings and other long-term assets. Both appear in the cash flow statement in the company's 10-K annual report, filed with the SEC.

Free cash flow is the cash left over to pay dividends, buy back shares or pay down debt. When you project it into the future, think separately about:

Revenue growth and how profit margins might change.
How much investment the company needs to keep growing.
Changes in working capital, meaning the cash tied up in inventory and in money customers owe.

3. The discount rate: WACC

WACC stands for weighted average cost of capital. A company is financed partly by shareholders (equity) and partly by lenders (debt). Each group expects a return. WACC blends those two costs according to how much of each the company uses:

WACC = (E ÷ V) × Re + (D ÷ V) × Rd × (1 − T)

Component	Meaning	Practical note
E ÷ V	Share of financing from equity	Use market value, not book value
Re	Cost of equity	Usually estimated with CAPM
D ÷ V	Share of financing from debt	Include interest-bearing debt
Rd × (1 − T)	After-tax cost of debt	T is the company's tax rate, found in the 10-K

Debt gets a tax adjustment because, in general, interest payments are tax-deductible for the company.

Estimating the cost of equity with CAPM

The Capital Asset Pricing Model (CAPM) is the most common way to estimate what shareholders expect:

Re = Risk-free rate + Beta × Equity risk premium

Risk-free rate: the return on an investment considered close to risk-free. For U.S. companies, analysts usually use the yield on the 10-year U.S. Treasury note. It changes every day, so look up the current figure from the U.S. Treasury or another official source at the time you do your analysis.
Beta: how much a stock has tended to move compared with the overall market. A beta above 1 means it has moved more than the market; below 1, less.
Equity risk premium: the extra return investors demand for owning stocks instead of risk-free bonds. There is no official number; different sources publish different estimates, so state which one you use.

A higher WACC means you demand a higher return, which lowers the present value of future cash flows. That is why every component should be justified, not picked to reach a result you already wanted.

4. Terminal value

You cannot project cash flows year by year forever. So analysts usually forecast five to ten years in detail, then estimate a terminal value for everything after that. A common method is the Gordon growth model:

Terminal value = Next year's FCF ÷ (WACC − g)

Here, g is the growth rate you assume the company can sustain forever.

A round-number example, for illustration only: if next year's free cash flow after the forecast period is $10 million, WACC is 9% and g is 3%, the terminal value is $10 million ÷ 0.06, or about $167 million. If you change g to 4%, it becomes $10 million ÷ 0.05, or $200 million. One percentage point changed the result by about a fifth.

Two lessons follow. First, the smaller the gap between WACC and g, the more sensitive the result. Second, assuming a company will grow forever faster than the economy as a whole is rarely realistic.

5. Scenarios and sensitivity

Instead of producing a single number, value the company under several scenarios: optimistic, base case and pessimistic.

Change one key assumption at a time to see which one drives the result most.
Make sure growth, investment and margins are consistent with each other. Fast growth usually requires heavy investment.
Build in a margin of safety: only consider a stock attractive if the market price is well below your estimate, to allow for errors.

Common mistakes

Using net income instead of cash flow. A DCF discounts cash, not accounting profit.
Choosing a WACC without explaining it. Each component needs a source or a clear reason.
Projecting unrealistic growth. Growing far faster than the industry for many years is a fragile assumption.
Showing a single number. Without a range, the result looks more precise than it is.

A simple checklist

Build free cash flow from operating cash flow minus capital expenditures.
Write down every growth and margin assumption.
Calculate WACC using market values and a current risk-free rate.
Check that the gap between WACC and g is reasonable.
Run optimistic, base and pessimistic scenarios.
Compare the result with other methods, such as valuation multiples.

Frequently asked questions

How many years should a DCF forecast cover?

Typically five to ten years, long enough for the business to reach a more stable stage. The longer the forecast, the more uncertain each assumption becomes.

What perpetual growth rate is reasonable?

It should not exceed the long-term nominal growth of the economy for long. If your valuation only works with an optimistic perpetual growth rate, it is a fragile valuation.

Why use the 10-year Treasury as the risk-free rate?

U.S. Treasury securities are backed by the federal government and are widely treated as the closest thing to a risk-free asset in dollars. The 10-year maturity roughly matches the long horizon of a stock investment, which is why it is a common convention.

Should I use a DCF or valuation multiples?

They work best together. Multiples, like the P/E ratio, give a quick market reference. A DCF forces you to spell out your assumptions. Comparing both helps catch mistakes.

The real value of a DCF is not the final number but the process: it makes you understand the business and admit what you do not know. This article is educational and is not investment advice.

See it with real companies

Each of these pages shows the company's dated figures and how it compares with its sector:

Keep learning

An article from the Fintols blog, adapted for US investors. Educational content, not investment advice.