Price-to-Book, Price-to-Sales & Price-to-Cash-Flow

Builds onJustified Leading P/E — if this page feels steep, start there.

P/B = \frac{P_0}{BVPS} \qquad P/S = \frac{P_0}{SPS} \qquad P/CF = \frac{P_0}{CFPS}

$P_0$: the current share price
$BVPS$: book value per share: shareholders' equity divided by shares outstanding
$SPS$: sales (revenue) per share
$CFPS$: cash flow per share (often operating cash flow ÷ shares outstanding)

Why it must be true

P/E is the most famous valuation multiple, but it breaks down the moment earnings do — a loss-making company has no meaningful P/E at all. These three multiples exist precisely because their denominators rarely go negative or vanish: book value, sales, and cash flow are all steadier, harder-to-manipulate yardsticks than an accounting earnings figure that management has more room to shape.

Each answers the same underlying question — "how many dollars is the market paying for one dollar of THIS" — just measured against a different foundation: net assets (P/B), the top line (P/S), or operating cash (P/CF). A cheap P/E next to an expensive P/B is itself a finding: the market may be paying up for assets an earnings-only lens would miss.

The derivation

Each ratio is the same construction — price per share over some per-share fundamental — applied to a different line of the financial statements:

P/B = \frac{\text{Price per share}}{\text{Book value per share}}

P/S = \frac{\text{Price per share}}{\text{Sales per share}}

P/CF = \frac{\text{Price per share}}{\text{Cash flow per share}}

All three collapse to the same idea as P/E — price divided by a fundamental — just with denominators chosen for their resistance to accounting distortion and their ability to stay positive even when earnings can't.

When to reach for it

Valuing a company where earnings are negative, volatile, or suspected of being managed — or simply cross-checking a P/E-based view against asset, revenue, and cash-flow-based multiples.

Listen for

“price-to-book (P/B) / price-to-sales (P/S) / price-to-cash-flow (P/CF)”“trading below book value”“valuing a company with no earnings (or negative earnings)”“multiple based on assets / revenue / cash flow instead of earnings”

Back-of-the-envelope

Estimate it in your head first — then the calculator only confirms.

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P/B below 1.0 means the market values the equity below its own book net worth — historically a value-investing screen, though it can also mean the market doubts the book value itself (e.g. impaired assets).
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P/S is scale-blind to profitability entirely — a company can have an attractive P/S and still be unprofitable. Never read P/S alone as a verdict on quality.
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All three multiples move in the SAME direction as price for a fixed denominator — if price rises and a computed multiple falls, the denominator was likely swapped into the numerator.

Traps in applying it

✗Inverting the ratio (denominator over price) — all three are price ON TOP, per-share fundamental on the bottom.
✗Mixing per-share and total-company figures — price is per share, so the denominator must also be stated per share, not as a company-wide total.
✗Treating a low multiple as automatically 'cheap' without checking WHY it's low — a low P/B can mean a genuinely undervalued asset base, or a business the market rightly doubts.

Limits & criticisms

Book value can be a poor proxy for economic value — intangible-heavy businesses (software, brands) carry little on the balance sheet despite real economic worth, making P/B nearly meaningless for them. P/S ignores the cost side entirely, so it can't distinguish a lean, profitable business from a bloated, money-losing one at the same revenue. And "cash flow" in P/CF is not standardized the way earnings are — different analysts include different items, so the ratio isn't always comparable across sources without checking the definition used.

Where it came from

Price-to-book is one of the oldest valuation anchors in equity analysis, central to Graham and Dodd's Security Analysis (1934) as a floor-value check — a stock trading below book value was, in the original value-investing tradition, potentially trading below its liquidation worth. Price-to-sales was popularized by Kenneth Fisher's Super Stocks (1984) specifically as a tool for valuing young or cyclical companies with volatile or negative earnings. Price-to-cash-flow grew alongside the recognition, through the 1980s–90s accounting scandals, that reported earnings could be managed far more easily than cash actually moving through the business.

One identity, 3 questions

The exam can hide any variable. Each face below is the same equation solved for a different unknown — drill them separately.

Price over book value

P/B = \frac{P_0}{BVPS}

The asset-anchored face: what the market pays per dollar of net assets on the books.

Drill this face →

Price over sales

P/S = \frac{P_0}{SPS}

The revenue-anchored face: usable even when earnings are negative or unreliable.

Drill this face →

Price over cash flow

P/CF = \frac{P_0}{CFPS}

The cash-anchored face: harder to manage than accounting earnings.

Drill this face →

On the BA II Plus

Worked example: A stock trades at $62.00. Book value per share is $13.00, sales per share $38.00, and cash flow per share $9.00. Compute price-to-sales.

1.62 [÷] 38 [=]price over the per-share fundamental

→ 1.6316

Drill this formula Back to the library