Book value is total assets minus total liabilities: what the balance sheet says shareholders own. It is an accounting figure recorded at historical cost, not an estimate of what the business is worth. For companies whose value sits in brands, software or research, book value understates reality badly.
How to calculate it
Book value equals total assets less total liabilities, which is the same as total shareholders' equity on the balance sheet. Book value per share divides that by diluted shares outstanding. Price-to-book compares the share price to that per-share figure, so a P/B of 1.0 means the market is paying exactly what the accounting says the equity is worth.
Tangible book value goes one step further and subtracts goodwill and other intangibles. That is the more conservative version, and for a bank or an insurer it is the one people actually quote.
Why the number drifts from reality
Assets sit on the balance sheet at what was paid for them, less depreciation. A warehouse bought in 1994 is carried near zero and might be worth a great deal. That is the harmless direction of error.
The damaging direction is what never gets recorded at all. Research spending, brand building and software development are expensed as they happen, so a company that has spent two decades building something genuinely valuable can show almost no book value for it. Buy that same asset through an acquisition and it appears as goodwill. The accounting treats built and bought value completely differently, which makes P/B incomparable across two companies that grew in different ways.
What a low price-to-book usually means now
Value investing was built on P/B in an era when most companies owned physical things. Applied today to a software business, a low P/B mostly identifies companies with heavy balance sheets and weak returns. Screening for it tends to surface capital-intensive businesses in structural decline rather than bargains, which is the same failure mode as screening for a low P/E.
The more useful question is not what the assets cost but what they earn. That is ROIC, and it answers the question P/B was being used as a proxy for.
The two places it still works
Financials. A bank's assets are loans and securities, marked closer to current value and genuinely comparable between institutions. Price-to-tangible-book is a real valuation tool for banks and insurers in a way it is not for anyone else.
As a floor in liquidation. If a company is being wound up or trades below net current asset value, book value bounds what shareholders might recover. This is rare, and usually rare for a reason.
Outside those two cases, treat book value as a description of financing history rather than a measure of worth. Intrinsic value comes from future cash, and the balance sheet records the past.
See what a balance sheet is actually telling you
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Frequently asked questions
Related
- How to read a balance sheet, where shareholders' equity comes from and what sits above it.
- Intrinsic value, what a business is actually worth, which the balance sheet does not tell you.
- ROIC, what the assets earn, which is the question price-to-book was standing in for.
- P/E ratio, the other ratio that mostly finds companies whose numbers are about to fall.