What Is the Price-to-Book Ratio (P/B)?
The price-to-book (P/B) ratio compares a stock's share price to its book value per share — the company's assets minus liabilities, divided by shares. It shows how the market values a company versus its accounting net worth.
How the P/B Ratio Is Calculated
The formula is simple: P/B = share price ÷ book value per share. Book value is a company's total assets minus its total liabilities, a figure also known as shareholders' equity. Divide that equity by the number of shares outstanding and you get book value per share.
Say a stock trades at $30 and has a book value of $15 per share. Its P/B ratio is $30 ÷ $15 = 2, meaning investors are paying twice the accounting net worth for each share. You will find shareholders' equity on the balance sheet in a company's 10-K, so you can calculate P/B yourself for any stock you are researching.
What a High or Low P/B Means
A P/B of 1 means the market price equals book value — investors are paying exactly what the company's net assets are worth on paper. A P/B above 1 means the market is paying a premium over book value, which usually signals that investors expect future growth or that they value intangibles the balance sheet does not fully capture, such as a strong brand, patents, or customer loyalty.
A P/B below 1 means the market values the company at less than its book value. That can look like a bargain — you are buying assets for less than their stated worth — but it can just as easily reflect a struggling business that investors expect to erode. The ratio alone cannot tell you which story is true.
Where P/B Works Best
P/B is most meaningful for asset-heavy businesses whose value lives on the balance sheet. Banks, insurers, and manufacturers hold large amounts of tangible assets — loans, securities, factories, equipment — so their book value closely tracks what the company is really worth. For these industries, P/B is a genuinely useful yardstick and often a standard way analysts value them.
The ratio is far less useful for asset-light technology and services companies. A software firm's real value comes from code, brands, and talent, none of which show up as tangible assets, so its book value can be tiny and its P/B can look enormous even when the business is healthy. In those cases a high P/B is not automatically a warning — it just reflects the limits of the metric.
Using P/B With Other Metrics
P/B is strongest when read alongside other numbers rather than in isolation. Pairing it with the P/E ratio, return on equity (ROE), and a look at how much debt the company carries paints a much fuller picture. A low P/B combined with a high ROE can be genuinely attractive, because it means the company earns strong returns on its equity yet trades cheaply relative to that equity. A low P/B on its own, however, is often a value trap — a cheap-looking stock that stays cheap because the underlying business keeps deteriorating. Our guide to valuation metrics beyond P/E covers how these pieces fit together.
Practice Valuing Stocks Risk-Free
The best way to make P/B stick is to calculate it for real companies and see how it lines up with their price, ROE, and industry. You can do exactly that while paper trading with CustomStocks, a free simulator that lets you research and trade real companies at real market prices using virtual money — so you can test what P/B tells you without risking a cent.
Frequently Asked Questions
The price-to-book ratio is calculated by dividing a stock's share price by its book value per share. Book value per share is the company's total assets minus its total liabilities, divided by the number of shares outstanding. For example, a stock trading at $30 with a book value of $15 per share has a P/B ratio of 2.
There is no single good number, but a P/B below 1 can indicate a stock is priced below its accounting net worth, while a high P/B suggests the market expects growth or values intangible assets. What counts as attractive varies by industry, so P/B is best compared among similar companies rather than across the whole market.
A P/B below 1 means the market values the company at less than its book value — its assets minus liabilities. That can signal a potential bargain, but it can also be a warning that investors expect the business to lose value or struggle. A low P/B is a starting point for research, not an automatic buy signal.
P/B is most useful for companies with lots of tangible assets on their balance sheets, such as banks, insurers, and manufacturers, where book value closely reflects real worth. It is far less useful for asset-light technology or services companies, whose value comes largely from intangible things like brands and software that book value does not capture.
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