What Is the P/B Ratio (Price-to-Book)?
What Is the P/B Ratio?
The P/B ratio (price-to-book ratio) measures a company's share price relative to its book value per share, showing whether a stock is trading above or below its accounting net worth.
The price-to-book ratio, usually shortened to P/B ratio, compares a company's share price to its book value per share. Where the P/E ratio measures price against profit, the P/B ratio measures price against net worth, what the company would theoretically be left with if it sold everything it owns and paid off everything it owes.
It's the second half of what makes up the Graham Number, alongside the P/E ratio. Graham's formula caps a conservative purchase at no more than 15 times earnings and no more than 1.5 times book value, and that "1.5" is the P/B ceiling, expressed as a specific number rather than named explicitly in that article.
How It's Calculated
P/B Ratio = Share Price ÷ BVPS
Share price is the current market price of one share. BVPS is book value per share, shareholder equity divided by shares outstanding, the same figure used in the Graham Number calculation.
Take a stock trading at €25, with BVPS of €18.00:
€25 ÷ €18.00 ≈ 1.39
That result, 1.39, means the stock is trading at roughly 1.39 times its book value. A stock trading exactly at its book value would show a P/B of 1.0, and one trading below book value would show a P/B under 1.0.
What a Higher or Lower P/B Means
A P/B under 1.0 means the stock is trading below its book value, sometimes described as trading "below book." Traditionally, value investors have treated this as a potential signal of undervaluation, the idea being that you could theoretically buy the whole company for less than its assets are worth on paper.
A P/B well above 1.0 means the market is valuing the company at a premium to its accounting net worth, which is extremely common and not inherently a red flag. It often reflects value the balance sheet doesn't fully capture, like a strong brand, valuable customer relationships, or high expected future profitability that isn't yet showing up in book value.
As with the P/E ratio, neither a high nor low P/B is automatically good or bad on its own. A very low P/B can signal a genuine bargain, or it can signal a company in real distress that the market has correctly priced down, sometimes the same "value trap" pattern covered in the P/E ratio article.
Where P/B Is Most Useful
The P/B ratio tends to be more meaningful for certain kinds of businesses than others.
It works best for asset-heavy companies, banks, insurers, industrials, real estate, where a large share of the company's value genuinely sits in tangible assets on the balance sheet. For these businesses, book value is a reasonably faithful proxy for real economic worth.
It's much less useful for asset-light companies, particularly software, services, and other businesses where most of the value comes from things like intellectual property, brand, or customer relationships rather than physical assets. These companies can show very high P/B ratios that look expensive on paper while still being reasonably priced relative to their actual earnings power, since book value simply isn't capturing where their value comes from.
Limitations
The P/B ratio inherits every limitation already covered in the book value per share article, since it's built directly on that figure. Intangible assets, goodwill, and accounting choices can all distort what book value actually represents, which means the P/B ratio inherits that same distortion.
It also doesn't account for profitability at all. A company can have a low P/B while barely earning any profit, or even losing money, in which case the low ratio isn't really a bargain, it's a reflection of a struggling business, not an "undervalued" one. This is exactly why Graham combined P/B with P/E in the Graham Number rather than relying on either ratio alone, since checking both at once catches cases where one ratio looks attractive but the other reveals the real picture. Pairing it with return on equity is another common way to check that a low P/B isn't just a low-quality business.
And like the P/E ratio, comparing P/B ratios across different industries usually isn't meaningful. A P/B of 3 might be unremarkable for one type of business and unusually high for another, so it's most useful compared against similar companies or against a company's own historical range.
FAQ
What does a P/B ratio below 1 mean?
It means the stock is trading below its book value, sometimes described as trading "below book." Traditionally, value investors have treated this as a potential signal of undervaluation, the idea being that you could theoretically buy the whole company for less than its assets are worth on paper.
Is a low P/B ratio always a good sign?
No. A low P/B can reflect a genuine bargain, or it can reflect a company in real distress that the market has correctly priced down, the same "value trap" pattern that shows up with the P/E ratio. A low P/B alone doesn't account for profitability, so it's worth checking earnings before treating it as a discount.
Nothing on this site is financial advice. It's a personal record of my own research and decisions, shared for transparency, not as a recommendation to buy or sell anything.