Price-to-Book Ratio Calculator
Calculate the price-to-book (P/B) ratio to compare a stock's market price to its accounting book value per share. Investors use this to identify undervalued or overvalued stocks.
About this calculator
The price-to-book (P/B) ratio is a valuation metric that compares a company's current market price per share to its book value per share. The formula is: P/B Ratio = Market Price per Share / Book Value per Share. Book value per share is calculated as total shareholders' equity divided by total shares outstanding, representing the net asset value attributable to each share. A P/B ratio below 1.0 suggests the stock trades at a discount to its accounting net assets — potentially undervalued — while a ratio significantly above 1.0 indicates the market expects future growth or strong earnings power beyond what the balance sheet reflects. The P/B ratio is especially useful for valuing banks, insurance companies, and asset-heavy businesses where tangible assets dominate. Growth and tech companies often carry high P/B ratios because their value resides in intangibles like intellectual property and brand.
How to use
Suppose a bank's stock is trading at $45 per share, and its book value per share is $30. Enter Market Price per Share = $45 and Book Value per Share = $30. The calculator computes: P/B Ratio = 45 / 30 = 1.5. This means investors are paying $1.50 for every $1.00 of the bank's net book assets. Compared to an industry average P/B of 1.2, this bank is trading at a modest premium, suggesting the market expects above-average profitability or growth.
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 net book value — in theory, you are buying $1.00 of assets for less than $1.00. This can indicate the stock is undervalued and represents a bargain, which is why value investors like Warren Buffett historically used P/B as a screening tool. However, a low P/B can also signal genuine problems: declining earnings, poor asset quality, or impending write-downs. Always investigate why the ratio is below 1 before concluding a stock is cheap.
How do I calculate book value per share if I only have the balance sheet?
Book value per share is calculated by dividing total shareholders' equity by the number of shares outstanding: Book Value per Share = Total Shareholders' Equity / Shares Outstanding. Shareholders' equity is found on the balance sheet as total assets minus total liabilities. Some analysts use tangible book value, which further subtracts intangible assets like goodwill, for a more conservative measure. You can find both figures in a company's quarterly or annual financial statements (10-Q or 10-K filings).
Why is the price-to-book ratio more useful for some industries than others?
The P/B ratio works best for industries where assets are tangible and accurately reflected on the balance sheet — such as banking, insurance, real estate, and manufacturing. In these sectors, the book value meaningfully represents the company's economic worth. For technology, pharmaceutical, or consumer brand companies, a large portion of value comes from intangible assets like patents, software, and brand equity that accounting standards do not fully capture. This makes P/B less meaningful for those sectors and causes their ratios to appear artificially high.