Price-to-Sales Ratio (P/S)

What it is

The price-to-sales ratio divides a company's market capitalisation by its annual revenue. If a company has a market cap of £500m and generates £250m of revenue, its P/S ratio is 2.0x. You're paying £2 for every pound of annual sales.

Unlike the P/E ratio, P/S works even when a company has no earnings. This makes it the dominant valuation tool for early-stage, pre-profit businesses — technology companies, biotech, growth retail — where the earnings line is negative but the revenue trajectory is the investment thesis.

How to calculate it

On a per-share basis: P/S = Share Price ÷ Revenue Per Share

Some analysts prefer EV/Sales (enterprise value divided by revenue) to account for differences in capital structure. EV/Sales is particularly useful for comparing companies with different debt levels — a highly leveraged competitor to a debt-free one — where pure market cap to revenue would be misleading.

Why it's the measure of last resort

P/S has one significant weakness: revenue is not profit. A company generating £1 billion of revenue at a 2% operating margin is a very different business from one generating £1 billion at a 25% margin. Valuing both on the same P/S multiple would be deeply misleading.

This is why P/S is most useful as a starting point or when comparing companies within the same sector with similar margin profiles — tech-to-tech, retailer-to-retailer. Used across sectors, it's almost meaningless.

Gross margin-adjusted P/S helps: divide the P/S by the gross margin percentage to get a sense of how much you're paying for actual economic value creation rather than just revenue volume. Two companies at 8x P/S, one with 80% gross margin and one with 20% gross margin, are dramatically different propositions.

When it's most useful

Pre-profit growth companies: If a software company is investing aggressively in sales and R&D — burning cash to build market share — the earnings line will be negative or near zero. The investment thesis is the revenue growth rate and the potential margin at scale. P/S is the appropriate lens here.

Sector relative valuation: Within UK software, for example, comparing Sage Group's P/S to Kainos Group's P/S gives a calibrated sense of how the market is pricing growth and quality across peers.

Distressed businesses: A company in turnaround that has recently returned to profitability may have minimal EPS, making P/E temporarily distorted. P/S gives a floor sense of value relative to the revenue base.

The dot-com lesson

In 1999–2000, internet companies were valued on P/S multiples of 50–100x or more. The argument was that revenue was what mattered — profits would come later, at scale. Some of that was true (Amazon eventually justified its valuation). Most of it wasn't — the underlying businesses had no path to profitability at any realistic margin.

The same pattern repeated in 2020–2021 with loss-making SaaS companies, UK biotech, and fintech. P/S multiples of 30–50x were widespread. Many subsequently fell 80–90%.

P/S should never be used in isolation and should always be anchored to a plausible margin trajectory. Revenue at any price is not value creation.

UK context

UK technology stocks historically traded at a discount to US peers on P/S — partly reflecting the relative immaturity of the UK tech ecosystem and lower analyst coverage, partly reflecting genuine valuation conservatism among UK institutional investors. This discount has narrowed in recent years but remains observable.

Not financial advice. P/S analysis should always be anchored to margin trajectory and competitive position.