What is the Graham Number?
The Graham number quantifies stock valuation by merging two fundamental metrics: earnings per share (EPS) and book value per share (BVPS). This single figure represents a theoretical price ceiling that suggests when a stock may be undervalued. If a company trades below its Graham number, the metric implies downside protection and potential margin of safety. Conversely, stocks trading above this threshold appear expensive relative to their earnings power and tangible asset base.
Named after legendary investor Benjamin Graham, this approach reflects value investing philosophy: purchasing quality businesses at prices significantly below their calculated worth. The metric works best for established, profitable companies with positive net income and reasonable balance sheets. It does not account for growth trajectories, competitive moats, or qualitative business factors—limitations that require additional analysis before making investment decisions.
Graham Number Formula
The Graham number calculation relies on two intermediate steps: deriving earnings per share and book value per share from fundamental financial statements, then applying the core formula.
Earnings per Share (EPS) = TTM Net Income ÷ Common Outstanding Shares
Book Value per Share (BVPS) = Shareholders' Equity ÷ Common Outstanding Shares
Graham Number (GN) = √(22.5 × EPS × BVPS)
EPS— Trailing twelve-month earnings divided by weighted average common shares outstandingBVPS— Total common shareholders' equity divided by issued common sharesGN— The resulting fair value estimate, expressed in currency per share22.5— A constant derived from Graham's original formula assuming a 15 P/E ratio and 1.5 P/B ratio
Eligibility Criteria and Real-World Example
The Graham number applies reliably only when two strict conditions are met: the stock's price-to-earnings ratio must not exceed 15, and its price-to-book ratio must not exceed 1.5 (or their product must remain below 22.5). These guardrails ensure the formula operates within Graham's original assumptions about market valuations.
Consider TD Synnex Corporation prior to Q2 2020 earnings: with a trailing EPS of $10.47 and BVPS of $75.82, both PE (9.2) and PB (1.3) ratios cleared the thresholds. The calculation yielded:
GN = √(22.5 × 10.47 × 75.82) = √19,882.48 ≈ $140.87
This suggested that any purchase price substantially below $140 offered margin of safety, though actual returns depend on how the business subsequently performed and whether competitive dynamics shifted.
Limitations and When to Seek Alternatives
The Graham number ignores critical metrics such as free cash flow generation, EBITDA margins, competitive positioning, and management quality. It also fails for unprofitable companies or those with deteriorating earnings. When these constraints apply, alternative valuation frameworks become necessary:
- EBITDA multiples: Preferred for asset-heavy industries, businesses with significant depreciation, or cyclical sectors where net income fluctuates sharply.
- EV-to-sales ratios: Useful for companies burning cash but growing rapidly, or industries where profitability differs structurally from peers.
- Discounted cash flow (DCF): Captures the present value of all future cash distributions, accounting for growth rates and terminal value assumptions.
The Graham number remains a useful screening filter but should never stand alone as investment justification.
Key Pitfalls and Best Practices
Successful application of the Graham number requires understanding where it succeeds and fails.
- Don't ignore the ratio prerequisites — Stocks violating the P/E ≤ 15 or P/B ≤ 1.5 conditions fall outside the formula's reliable range. Applying it anyway produces mathematically valid but strategically misleading results. Always verify both ratios before trusting the Graham number output.
- Account for one-time items in earnings — TTM net income can be distorted by asset sales, restructuring charges, or litigation settlements. Adjust reported earnings to core operating performance before calculating EPS. Inflated earnings produce inflated Graham numbers and create false bargains.
- Cross-check with industry peers — A stock trading below its Graham number doesn't automatically signal undervaluation if competitors trade at much lower multiples. Sector-wide downgrades, technological disruption, or regulatory headwinds can justify depressed valuations that persist indefinitely.
- Monitor balance sheet quality — Book value per share assumes tangible asset values reflect realistic liquidation or earning power. Intangible assets, goodwill write-offs, and questionable accounting can inflate BVPS. Review the composition of shareholder equity and historical write-downs.