DCF vs Graham Number: which valuation should you trust?
A discounted cash flow model and Benjamin Graham's formula both try to answer the same question — what is this stock actually worth? — but they go about it in completely different ways. One forecasts the future; the other anchors to the present. Knowing when to use each matters.
Two philosophies of valuation
Every intrinsic value estimate has to deal with the same hard fact: a company's worth depends on cash it will generate in the future, which nobody knows. A discounted cash flow (DCF) model tackles this head-on by forecasting that future cash. The Graham Number sidesteps it entirely, anchoring value to what the company earns and owns today. Two honest attempts at the same question, from opposite directions.
The DCF approach
A DCF projects a company's free cash flow years into the future, then discounts those future cash flows back to today's value (because a pound next decade is worth less than a pound now). Add them up, and you get an estimate of intrinsic value.
Strength: it's the most theoretically complete method — it directly models what actually drives value, the cash a business produces over its life.
Weakness: it's only as good as its assumptions. Small changes to the growth rate or discount rate swing the answer enormously. Forecast 12% growth instead of 8%, and the valuation can change by half. "Garbage in, garbage out" is the standing criticism.
The Graham Number approach
Benjamin Graham — Buffett's teacher — wanted something simpler and more conservative, using only figures a company reports today: its earnings per share and its book value per share.
The 22.5 comes from Graham's rule that a defensive stock shouldn't trade above 15× earnings or 1.5× book value — and 15 × 1.5 = 22.5. The result is a rough ceiling on what a conservative investor should pay.
Strength: simple, objective, and uses no forecasts — so no room for wishful assumptions. It can't be gamed by an optimistic growth rate.
Weakness: it's blunt. It ignores growth entirely, which makes it far too pessimistic for high-growth or asset-light businesses — it barely works for a modern software company with little book value. It's a product of Graham's 1930s–40s world of industrial, asset-heavy firms.
Side by side
| DCF | Graham Number | |
|---|---|---|
| Based on | Forecast future cash flows | Current earnings & book value |
| Accounts for growth? | Yes — central to it | No — ignores it entirely |
| Main risk | Wrong assumptions swing the answer | Too pessimistic for growth stocks |
| Best suited to | Businesses with forecastable cash flows | Stable, asset-heavy, mature firms |
| Objectivity | Depends heavily on the analyst | Fully objective, formula-driven |
Which should you trust?
Neither, exclusively. They're most useful together, as a cross-check. If a careful DCF and the Graham Number both suggest a stock is undervalued, that agreement is a strong signal — two very different methods pointing the same way. When they disagree wildly, that's informative too: it usually means the company's value hinges on future growth (which the DCF captures and Graham ignores), so you'd better be confident in that growth.
The Graham Number works best as a quick, conservative sanity check. The DCF works best when you genuinely understand the business well enough to forecast it. Used together, they cover each other's blind spots.
Common questions
What's the difference between DCF and the Graham Number?
A DCF estimates value by forecasting and discounting a company's future cash flows, accounting for growth. The Graham Number uses only current earnings and book value with a fixed formula, ignoring growth. DCF is more complete but assumption-heavy; the Graham Number is simpler but blunter.
Is the Graham Number still useful today?
It works well as a quick, conservative sanity check for stable, asset-heavy businesses. It's far less useful for high-growth or asset-light companies like software firms, because it ignores growth and leans on book value, which such companies have little of.
Why do DCF valuations vary so much?
Because a DCF depends heavily on assumptions — especially the growth rate and discount rate. Small changes to those inputs can swing the valuation dramatically, which is why the same company can be valued very differently by different analysts.
Should I use DCF or the Graham Number?
Use both as a cross-check. When they agree a stock is cheap, that's a stronger signal than either alone. When they disagree, it usually means the valuation hinges on future growth — which the DCF captures and the Graham Number ignores.