How the Price to Book Ratio Calculator works
The price-to-book (P/B) ratio compares what the market is willing to pay for a company's shares against the accounting value of its net assets. It answers a specific question: for every dollar of book value — assets minus liabilities, minus any preferred stock claim — how many dollars is the market paying?
The formula
The ratio is calculated in two steps. First, book value per share:
Book Value per Share = (Total Stockholders' Equity − Preferred Equity) ÷ Common Shares Outstanding
Then the P/B ratio itself:
P/B Ratio = Market Price per Share ÷ Book Value per Share
Preferred equity is subtracted first because preferred shareholders have a priority claim on assets ahead of common shareholders — only what remains after that claim belongs to the common shares in the denominator.
Worked example
Take a company trading at $45.00 per share, with total stockholders' equity of $1,200,000,000, no preferred stock, and 100,000,000 shares outstanding. Book value per share is $1,200,000,000 ÷ 100,000,000 = $12.00. The P/B ratio is then $45.00 ÷ $12.00 = 3.75 — the market is paying $3.75 for every $1.00 of the company's net assets.
What moves the ratio most
- Market price: the numerator moves directly with the stock price, so day-to-day price swings shift the ratio even when nothing about the underlying business has changed.
- Preferred stock: a large preferred balance shrinks the equity available to common shareholders, raising book value's denominator effect and pushing the P/B ratio higher for the same price and equity.
- Share count: buybacks reduce shares outstanding, which raises book value per share (all else equal) and lowers the P/B ratio; new share issuance works in the opposite direction.
What the ratio does and does not capture
Book value reflects historical accounting entries — original cost, depreciation, and any write-downs — not current market value or future earning power. That makes P/B most informative for asset-heavy businesses like banks, insurers, and REITs, where balance-sheet assets closely track economic value. It is far less informative for asset-light businesses whose value comes mostly from intangibles — brands, software, or people — that accounting book value does not capture. A P/B ratio, on its own, does not indicate whether a stock is a good or bad investment; it is one input to compare against a company's own history, its industry peers, and its profitability.