The Graham number formula is one of the most respected valuation tools in value investing. Benjamin Graham created it. He is the father of value investing and author of the book the intelligent investor. The formula helps investors calculate the maximum price an investor should pay for a stock. It uses two inputs: earnings per share EPS and book value per share. The output sets a ceiling on what a defensive investor should pay for a given stock.
This guide explains how the number formula works and breaks down each part of the math. It also shows where the formula fits in a broader stock evaluation process. The ValueMarkers stock screener lets investors filter stocks by Graham number and compare results across sectors.
What Is the Graham Number?
The Graham number is a single figure that estimates the fair value of a stock. It combines two financial metrics into one calculation. The first is earnings per share EPS. The second is book value per share.
By using both, the formula captures a company's earning power and its asset backing at the same time. Benjamin Graham or his followers refined this approach over decades. The idea holds that a stock's price should reflect both what a company earns and what it owns.
A stock that trades below its Graham number may offer a margin of safety. This means the investor pays less than the estimated fair value, which leaves room for error. The Graham number or Benjamin Graham's valuation method stays popular because the calculation requires no complex forecasting. All an investor needs is the most recent earnings per share EPS figure and the current book value per share from the balance sheet.
The Graham Number Formula
The Graham Number equals the square root of 22.5 times earnings per share times book value per share. The 22.5 multiplier times the ratio of price to earnings and price to book comes from Graham's conservative stock selection rules.
Graham held that a defensive investor should pay no more than 15 times the earnings P E ratio. He also set a ceiling of 1.5 times the book for the ratio of price to book. The product of those two limits yields the 22.5 constant that anchors the formula.
To calculate the Graham number, start with the trailing twelve-month earnings per share EPS from the income statement. Then find the most recent book value per share from the balance sheet.
Multiply the share EPS and book value together. Apply the 22.5 multiplier to that product. Compute the square root to arrive at the maximum price a defensive investor should pay for that stock.
A Step-by-Step Example
Suppose a company reports earnings per share of four dollars and a book value per share of twenty dollars. The product of those two figures is eighty. Multiplying eighty by 22.5 produces 1,800. The square root of 1,800 is about 42.43 dollars.
The Graham number formula sets the ceiling at roughly 42.43 dollars for this stock. If the current stock price sits below that level, the stock may be undervalued. If the stock price sits above it, the stock may be overpriced relative to its earnings and book value.
The gap between the Graham number and the stock price is the margin of safety. A larger gap means a bigger cushion against errors or setbacks. Graham stressed that this margin of safety is the central concept of sound investing. It shields the investor from analytical mistakes and unforeseen problems.
Why the Formula Uses Both Earnings and Book Value
Many valuation methods examine only one metric, whether earnings or assets. The Graham number formula stands out because it uses both earnings and book value per share in one calculation. This dual approach helps guard against common valuation traps.
A company with strong earnings but low book value may be priced for perfection. If profits drop, the stock has little asset backing to support its price. A company with high book value but weak earnings may hold assets that fail to produce adequate returns.
By requiring both metrics to be solid, the formula filters out stocks that are strong on one side but weak on the other. Graham saw this balance as essential for the defensive investor. The share EPS and book value per share inputs work together. They give a more balanced picture of intrinsic value than either metric alone.
Where the Formula Works Best
The number formula works best for established companies in traditional industries with meaningful tangible assets. Banks, insurance firms, manufacturers, and utilities suit Graham number evaluation well. Their book values reflect real economic worth because their balance sheets hold physical assets and financial instruments.
Value investors who focus on these sectors often use the Graham number as a first screen. They filter thousands of stocks down to a shorter list that trades below the calculated Graham number. Deeper research then shows which candidates merit a capital commitment. The ValueMarkers glossary explains book value, tangible assets, and related terms.
The formula also works well during broad market declines. Falling prices push more companies below their Graham number thresholds. Patient investors who keep target price lists can act when conditions create buying opportunities.
The Graham Number in Modern Markets
Market conditions have shifted since Graham first outlined his principles. Investors today should consider how those shifts affect the formula. Interest rates, sector mix, and the rising share of intangible assets in corporate balance sheets all matter.
During periods of low interest rates, stocks tend to trade at higher multiples. Fewer companies fall below their Graham number in those conditions. Rising rate environments often push valuations lower and create more formula-based opportunities.
Despite these shifts, the core logic behind the Graham number remains sound. Buying stocks below a conservative fair value based on current earnings and current assets provides a disciplined framework. It protects investors from overpaying during periods of excess optimism.
Using the Graham Number Alongside Other Metrics
The Graham number gains strength when paired with measures that address its blind spots. Comparing the Graham number to a discounted cash flow estimate helps investors gauge whether future growth adds value beyond what the formula captures.
The ratio of price to book value and the earnings P E ratio that underpin the 22.5 constant can also be examined on their own. A stock that passes the Graham number test but carries an unusually low price to book ratio may warrant extra review. The low book value could reflect asset write-downs rather than a genuine bargain.
Debt levels deserve attention as well. The Graham number does not factor in leverage directly. A company with heavy debt may appear cheap on a Graham number basis while carrying financial risk that the formula misses. Reviewing debt-to-equity alongside the Graham number helps investors avoid names with excessive balance sheet risk.
Limitations of the Graham Number
The formula has clear limits that investors should grasp. First, the Graham number does not account for growth. A fast-growing company may deserve a higher price than the formula suggests. It treats all earnings the same regardless of growth rates.
Second, the formula struggles with asset-light businesses. Technology firms, software companies, and service businesses often carry minimal book value per share despite strong profits. Their value comes from intellectual property or network effects rather than physical assets.
Third, companies with negative earnings cannot be evaluated with this formula. The math requires a positive product inside the square root. This rules out turnaround situations and early-stage companies.
Fourth, the 22.5 multiplier reflects Graham's views from a different era. Some modern investors adjust the multiplier based on current conditions or sector norms. No consensus exists on the right adjustment.
Common Mistakes When Using the Formula
Several errors can lead investors astray when applying the Graham number formula. The most frequent involves using projected earnings rather than actual trailing figures. Graham insisted on reported data. Forecasts introduce uncertainty that the formula was not built to handle.
Another common error involves ignoring the quality of book value. Not all assets carry genuine worth equal to their stated amounts. Inventory may be outdated. Receivables may prove uncollectible.
Recorded goodwill may exceed the real economic value of acquired assets. A careful investor checks whether the stated book value per share reflects real worth before trusting the output.
A third mistake involves treating the formula as the sole basis for a stock purchase. The Graham number works best as one tool among several. Combining the Graham number with debt ratios, cash flow trends, and management quality leads to stronger decisions across full market cycles.
How does the Graham number compare to other valuation methods?
The Graham number is simpler than discounted cash flow models and more conservative than most relative valuation approaches. The formula does not forecast future growth or estimate a discount rate. It anchors value in current earnings and current assets. This makes it a useful starting point for investors who prefer to pay for what a company has already demonstrated.
Can the Graham number formula be applied to all types of stocks?
The formula works best for mature, profitable companies with meaningful tangible assets, particularly in traditional industrial, financial, and utility sectors. The approach proves less useful for high-growth technology stocks, companies with negative earnings, or businesses whose value comes mainly from intangible assets. Investors in those categories should pair the Graham number with other tools that account for growth potential.