What Is the P/E Ratio?
Share price divided by earnings per share, with the earnings basis stated.
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Updated October 10, 2026
Simple answer
The price-to-earnings (P/E) ratio compares a stock's price to its earnings per share.
Why this matters
It's a quick gauge of how much you pay per dollar of profit.
Good signs
A lower multiple means paying less per unit of the specified earnings. It does not establish undervaluation.
Warning signs
A high multiple depends more heavily on expectations; a very low multiple can reflect risk or temporarily elevated earnings.
Easy mistake to make
Comparing P/E across sectors without context, or using negative/erratic earnings.
How Wall Street Score helps
Shown alongside valuation metrics on the stock page.
Calculate the ratio without treating it as a payback promise
Hypothetical price of $100 divided by annual earnings per share of $5 gives a P/E of 20. This is a valuation multiple, not a promise to recover your purchase price in 20 years. Earnings can change and are not automatically distributed as cash.
Use price and EPS for the same security, currency and split-adjusted share basis. ADRs and ordinary shares may represent different quantities of ownership.
State which earnings you use
Trailing P/E generally uses the past twelve months of earnings; forward P/E uses forecast earnings for a specified future period. Also distinguish reported from adjusted earnings and basic from diluted EPS. A provider’s adjustments can make its result differ from a calculation using the annual report.
At the same $100 price, $5 trailing EPS gives 20 while $4 forecast EPS gives 25. That difference describes the inputs, not a verified future earnings decline. Check the forecast date and horizon.
Know when the comparison becomes unhelpful
With zero EPS the ratio is undefined. With losses, a negative ratio should not be ranked as unusually cheap. Near-zero profits can produce extremely large multiples, and peak cyclical earnings can make a stock look deceptively inexpensive.
Compare similar businesses and review debt, cash generation, reinvestment and unusual gains or charges. A difference from peers or a historical average is a question to investigate, not a valuation conclusion.
Apply this to a real company
Search a stock and see the numbers in context.
Use the stock page to compare the Wall Street Score with revenue, EPS, cash, debt, valuation, risks and the company explanation.
See it on a stock
Further reading and verification
External references explain the underlying concepts and disclosures. Wall Street Score's examples and model interpretation are our own; these organizations do not endorse our scores.