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Price-to-Book Ratio (P/B): Formula, Sector Norms, and Value Traps

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The price-to-book ratio compares a stock's market price to the net worth on its balance sheet. Here is the formula, how it varies by sector, and how to tell genuine value from a value trap.

What the Price-to-Book Ratio Measures

The price-to-book ratio (P/B) tells you how much investors are willing to pay for every ₹1 of a company's net worth. Net worth here is book value — total assets minus total liabilities, the accounting value of what shareholders own if the company were wound up at the figures stated on its balance sheet.

A P/B of 1 means the market values the company at exactly its book net worth. A P/B above 1 means the market expects the assets to generate returns above their accounting value; a P/B below 1 means the market values the business at less than its stated net worth — which can signal cheapness or distress.

P/B leans on the book value per share, so the two metrics are best read together. Where earnings can swing or turn negative, book value tends to be more stable, which is why P/B is heavily used for banks, financials, and asset-heavy businesses.

The P/B Formula (Two Ways)

There are two equivalent ways to compute it. The per-share version divides the market price of one share by its book value per share.

P/B Ratio = Market Price per Share ÷ Book Value per Share

The whole-company version divides the total market capitalisation by the total net worth (shareholders' equity). It gives the identical answer.

P/B Ratio = Market Capitalisation ÷ Net Worth (Shareholders' Equity)

Book value per share itself is net worth divided by the number of shares outstanding. Net worth equals total assets minus total liabilities — equivalently, equity share capital plus reserves and surplus, after subtracting any revaluation reserves and intangibles if you want a stricter, tangible figure.

Worked Example

Take an illustrative mid-cap manufacturer, "Bharat Castings Ltd". The figures below are illustrative, not real.

ItemValue (illustrative)
Total assets₹4,000 crore
Total liabilities₹2,500 crore
Net worth (assets − liabilities)₹1,500 crore
Shares outstanding10 crore
Book value per share₹150
Market price per share₹450

Net worth is ₹4,000 cr − ₹2,500 cr = ₹1,500 crore. Book value per share is ₹1,500 cr ÷ 10 cr shares = ₹150. The P/B is then ₹450 ÷ ₹150 = 3.0. You get the same answer the whole-company way: market cap is ₹450 × 10 cr = ₹4,500 cr, and ₹4,500 cr ÷ ₹1,500 cr net worth = 3.0. Investors are paying ₹3 for every ₹1 of net worth — reasonable only if the company earns well above its cost of equity on that capital.

Why Sector Norms Matter

There is no universal "good" P/B. The right benchmark is the company's own sector, because what sits on the balance sheet differs wildly across industries.

Banks and financials carry their assets (loans, investments) on the balance sheet at near-fair values, so book value is meaningful and P/B is a primary valuation tool. Public-sector banks and many PSUs often trade near or below 1x book — the market discounts them for asset-quality worries, slower growth, or government-driven capital allocation. Strong private banks routinely trade at several times book.

IT services and FMCG are asset-light: their real value sits in brands, client relationships, talent and IP that accounting rules barely capture on the balance sheet. Their net worth is small relative to the cash they throw off, so P/B looks very high — double digits is normal — and the ratio becomes nearly useless on its own. For these, lean on the P/E ratio and enterprise value multiples instead.

SectorTypical P/B range (illustrative)Why
PSU banks / PSUs0.5x – 1.5xAsset-quality and capital-allocation concerns; book is meaningful
Strong private banks2x – 4xHigher ROE and growth lift the multiple
Manufacturing / autos1x – 4xHeavy tangible assets; book is a real anchor
IT services5x – 15xAsset-light; value is off-balance-sheet
FMCG / branded consumer10x – 30xBrand value not on the balance sheet

The ROE Link: What Justifies a High P/B

P/B does not float free of profitability — it is anchored to return on equity (ROE). A clean identity ties the two ratios together through the P/E multiple.

P/B = P/E × ROE

The intuition: a company that earns a high ROE on its book equity deserves a higher price per rupee of book, because each rupee of net worth is being put to more productive use. In valuation terms, if a firm's ROE exceeds its cost of equity, its fair value sits above book value (P/B above 1); if ROE is below the cost of equity, fair value sits below book (P/B under 1). So a 4x P/B on a business compounding equity at 25% ROE can be perfectly rational, while a 1.2x P/B on a firm earning 6% ROE may be expensive.

This is why you should never read P/B alone. Always pair it with ROE: a low P/B is only attractive when the underlying ROE is decent or improving.

Genuine Value vs a Value Trap

A sub-1 P/B looks like a bargain — you are buying assets for less than their stated worth. Sometimes it genuinely is. Often it is a value trap: the stock is cheap for a reason, and it stays cheap or gets cheaper.

The deciding question is whether the low P/B is paired with sound, recovering fundamentals or with permanent decline. Check these before concluding it is value:

  • ROE trend — is the company earning above its cost of equity, or is ROE stuck in single digits and falling? Persistently low ROE justifies a sub-1 P/B.
  • Asset quality — for a bank, a P/B under 1 frequently flags rising non-performing assets (NPAs) and the risk that book value is overstated.
  • Capital allocation — repeated value-destroying acquisitions, idle cash, or government-mandated spending in some PSUs erode returns.
  • Leverage and pledging — high debt-to-equity or heavy promoter pledging adds risk that justifies a discount.
  • Asset honesty — book value padded with goodwill, revalued land or stale receivables may not be recoverable; a tangible-book view is stricter.

Genuine value shows a low P/B alongside stable or improving ROE, clean assets, and a clear path to higher returns. A value trap shows a low P/B with deteriorating ROE and no catalyst — the market is pricing in further damage, not making a mistake.

Limitations of P/B

  • It is near-useless for asset-light businesses (IT, consumer, platforms) where the real value is off the balance sheet.
  • Book value is an accounting number — buybacks, write-downs, revaluations and depreciation policy can distort it, so two firms with the same P/B are not always comparable.
  • Intangibles like brand and goodwill can inflate book value; for a conservative read, strip them out toward a tangible-book basis.
  • P/B says nothing about growth or earnings power on its own — always combine it with ROE and the P/E ratio.
  • Negative net worth (accumulated losses exceeding equity) makes P/B meaningless or negative — the ratio breaks down for distressed firms.

Frequently asked questions

There is no single good number; it depends entirely on the sector and the company's return on equity. A P/B around 1 is a rough baseline, but a strong private bank earning high ROE may deserve 3x while a struggling PSU may warrant under 1x. Always compare a stock against its own industry peers, not against the broad market.

Divide the market price per share by the book value per share. Equivalently, divide total market capitalisation by net worth (shareholders' equity). Book value per share is net worth divided by shares outstanding, and net worth is total assets minus total liabilities. Both methods give the same P/B figure.

No. A P/B below 1 can mean the stock is undervalued, or it can be a value trap where the business is in decline. The deciding factor is return on equity: if ROE is decent or improving and assets are clean, low P/B may be genuine value. If ROE is falling and asset quality is weak, the cheapness is justified.

Banks carry assets close to fair value, so book value is meaningful and P/B is a primary tool for them. PSU banks often trade near or below 1x because the market discounts them for asset-quality risk, rising NPAs, slower growth, and government-driven capital allocation that can depress returns on equity.

These are asset-light businesses. Their real value sits in brands, intellectual property, client relationships and talent, which accounting rules barely record on the balance sheet. That keeps net worth small relative to their earning power, so P/B looks very high. For such firms, P/E and EV/EBITDA are far more useful valuation measures.

They are linked by the identity P/B equals P/E multiplied by ROE. A company earning a high return on equity deserves a higher price per rupee of book value. As a rule, if ROE exceeds the cost of equity, fair P/B is above 1; if ROE is below the cost of equity, fair P/B is below 1. Never read P/B without checking ROE.

P/B compares share price to book net worth and is most useful for asset-heavy firms and banks. P/E compares share price to earnings and works better for profitable, growing companies. P/B is more stable because book value rarely swings, while P/E breaks down when earnings are negative or erratic. The two are best used together.

Yes, if a company has negative net worth, meaning accumulated losses have wiped out its equity. In that case the P/B becomes negative or meaningless, since you cannot sensibly value a positive market price against negative book equity. Negative book value is itself a serious warning sign of financial distress.

Total book value includes intangibles like goodwill and brand value; tangible book value strips those out. For a conservative, liquidation-style view, tangible book value is stricter and safer, since intangibles may not be recoverable. Asset-heavy firms differ little between the two, but for acquisition-heavy companies the gap can be large.