The price-to-sales ratio measures what the market pays for each dollar of a company’s annual revenue. A P/S of 3 means investors are paying $3 for every $1 of sales the business makes in a year.
Its usefulness comes from what it does not require. Earnings can be negative, depressed by one bad quarter or reshaped by accounting choices; revenue is the hardest line in the accounts to bend and exists even for a company that has never made a profit. That makes P/S the multiple of last resort — and, correspondingly, the least informative one, because it says nothing at all about whether those sales earn anything.
Equivalently, share price divided by revenue per share. A variant called EV/Sales replaces market capitalisation with enterprise value, which makes it comparable across companies with very different amounts of debt.
A company with a market capitalisation of $6bn and revenue of $2bn over the last twelve months:
Whether 3.0 is dear depends entirely on what the sales convert into. At a net margin of 20% those sales produce $400m of profit and the company is on 15 times earnings; at a margin of 3% they produce $60m and it is on 100 times. The same P/S, two completely different propositions — which is the whole argument for never reading this ratio on its own.
Always pair it with a margin. P/S divided by net margin is, roughly, the P/E the company would have at that margin — and reading the two together turns a number that means little into a statement about what the business would be worth if it converted sales at a normal rate.
Compare within an industry and nowhere else. A software company and a grocery chain live at opposite ends of the margin spectrum, so their sales are simply not worth the same amount, and a cross-sector P/S comparison is a comparison of business models rather than of value.
In the app, P/S is one of the twenty-one key metrics on a company page, and Revenue is one of the seven lenses on the Fair Value tab — where the multiple is judged against the company’s own history rather than against a rule of thumb.
It comes into its own where earnings-based multiples break: a company still investing ahead of profit, a cyclical business at the bottom of its cycle, or a turnaround where this year’s loss says nothing about normal trading. It is also a useful stability check — revenue swings far less than profit, so a P/S history has a shape a P/E history often lacks.
It ignores profitability, cost structure and debt entirely: a company can double its revenue, destroy value doing so, and look cheaper on this measure. Because it uses market capitalisation rather than enterprise value, a heavily indebted business looks artificially inexpensive beside a debt-free one. And it flatters low-margin models by construction — a distributor turning over vast sums on thin margins will always screen cheap here, for no good reason.