Calculate the margin of safety between a stock's market price and intrinsic value. Determine buy price targets, upside potential, and get buy/hold/sell recommendations.
Benjamin Graham's formula for maximum fair price based on earnings and book value. A stock trading below its Graham Number may be undervalued by conservative standards.
"Confronted with a challenge to distill the secret of sound investment into three words, we venture the motto, Margin of Safety."
"The three most important words in investing are margin of safety."
"You want to buy a dollar bill for 50 cents. The margin of safety is always dependent on the price paid."
"The function of the margin of safety is, in essence, that of rendering unnecessary an accurate estimate of the future."
Every intrinsic value estimate contains assumptions that could be wrong — future growth rates, discount rates, competitive dynamics. Margin of safety acknowledges this uncertainty. By buying at a significant discount to your estimate, you create a buffer that protects your capital even if your analysis is partially wrong. A 30% margin of safety means the stock still has upside even if your intrinsic value estimate is 20% too high. This is why Graham called it the central concept of investment.
Each valuation method has strengths. DCF is the most comprehensive — it models future cash flows explicitly — but it's sensitive to terminal growth and discount rate assumptions. A 1% change in terminal growth can swing value by 20-30%. The Graham Number is deliberately conservative, anchoring to current earnings and book value with no growth assumption. Earnings Power Value (EPV) capitalizes current earnings without assuming growth, making it useful for mature companies. Professional value investors typically calculate all three and look for convergence.
The biggest mistake is anchoring margin of safety to an inflated intrinsic value estimate. If your DCF uses aggressive growth assumptions, even a 40% margin of safety may not protect you. Other pitfalls: (1) Ignoring balance sheet quality — a company with heavy debt has less room for error. (2) Using trailing earnings in cyclical businesses when earnings are at peak. (3) Confusing low price with margin of safety — a stock at $5 that's worth $3 has no margin of safety despite the low price. (4) Not updating your intrinsic value estimate as fundamentals change.
Margin of safety is calculated as (Intrinsic Value − Market Price) ÷ Intrinsic Value × 100. The buy price target applies your desired margin of safety to the intrinsic value: Buy Price = Intrinsic Value × (1 − Desired MoS%). Upside potential measures the percentage gain from the current market price to intrinsic value.
The Graham Number formula is √(22.5 × EPS × Book Value Per Share), derived from Graham's criteria that PE should not exceed 15 and P/B should not exceed 1.5. Earnings Power Value is calculated as Normalized Earnings ÷ Cost of Capital, representing the value of the company assuming no growth.