Price-to-Book Ratio Calculator
Calculate the price-to-book (P/B) ratio to compare a stock's market price against its accounting book value per share. Used by value investors to identify potentially undervalued or overvalued stocks.
About this calculator
The price-to-book (P/B) ratio compares what the market is willing to pay for a stock against the company's net asset value on its balance sheet. The formula is: P/B = market_price / book_value, where book value per share is total shareholders' equity divided by shares outstanding. A P/B ratio of 1.0 means the stock trades exactly at its book value. A ratio below 1.0 can indicate undervaluation — or financial distress — while a high P/B suggests the market expects strong future earnings or significant intangible value. Benjamin Graham considered stocks trading below book value as potentially bargain-priced. P/B is most meaningful for asset-heavy industries like banking and insurance, and less relevant for software or consulting firms where intangible assets dominate.
How to use
Suppose a bank stock trades at a market price of $42 per share, and its book value per share (equity divided by shares outstanding) is $35. Enter $42 in the Market Price field and $35 in the Book Value field. The calculator computes: P/B = $42 / $35 = 1.20. This means investors are paying $1.20 for every $1.00 of net assets. A P/B of 1.20 is modest and typical for a conservatively valued bank, suggesting neither extreme overvaluation nor distress.
Frequently asked questions
What does a price-to-book ratio below 1 mean for a stock?
A P/B ratio below 1.0 means the stock is trading for less than the company's accounting net asset value — in theory, you are buying $1 of assets for less than $1. This can signal undervaluation, particularly for asset-heavy businesses like banks or industrial companies. However, it can also reflect legitimate concerns: persistent losses eroding equity, poor return on assets, or balance sheet items that may be overstated. Investors should investigate the reason for a sub-1 P/B before concluding it is a bargain.
How is book value per share calculated for use in the P/B ratio?
Book value per share equals total shareholders' equity divided by the number of shares outstanding: Book Value per Share = (Total Assets − Total Liabilities) / Shares Outstanding. Shareholders' equity is found on the balance sheet and represents the residual value belonging to common stockholders after all liabilities are subtracted. It typically includes paid-in capital, retained earnings, and accumulated other comprehensive income. Goodwill and intangible assets are sometimes excluded to arrive at a 'tangible book value,' which is more conservative.
Why is the price-to-book ratio less useful for technology or software companies?
Technology and software companies derive most of their value from intangible assets — patents, software, brand, talent, and customer relationships — which are largely absent from the balance sheet under standard accounting rules. Internally developed intangibles are generally expensed rather than capitalized, so book value dramatically understates true economic value. As a result, P/B ratios for tech firms can appear extremely high (10x, 20x, or more) without necessarily indicating overvaluation. For such companies, analysts prefer metrics like price-to-sales, EV/EBITDA, or discounted cash flow analysis instead.