The formula
P/E is the share price divided by the company’s earnings per share (EPS) over a period, usually the last 12 months. If a stock trades at $100 and the company earned $5 per share, the P/E is 20. In plain words: you are paying $20 for every $1 of yearly profit.
This is an illustration, not a real company.
Trailing vs forward P/E
- Trailing P/E uses earnings from the past 12 months. It is based on facts but looks backward.
- Forward P/E uses analysts’ estimates of the next 12 months. It looks ahead but depends on forecasts that can be wrong.
What a high or low P/E suggests
A high P/E often means investors expect profits to grow quickly, so they will pay more today. A low P/E can mean a bargain, or it can mean the market expects trouble. Neither is automatically good or bad.
Different industries carry different typical P/Es. Fast-growing software companies tend to sit higher than banks or utilities, so comparing across industries can mislead. Compare a company with its own history and with close peers on our sector pages.
Where P/E breaks down
- Negative or tiny earnings. A company that loses money has no meaningful P/E.
- One-off items. A big sale of a business or a write-down can distort a single year.
- Cyclical companies. Earnings of miners or automakers swing with the economy, so P/E can look cheapest at the peak and most expensive at the bottom.
- Debt. P/E ignores how much a company owes. Look at debt and cash flow too.
Use it as a starting question
Think of P/E as a question, not an answer: why is this ratio what it is? Then look at growth, profit margins, debt, and how the business makes money. Our screener lets you sort tracked stocks by price and day moves, and every stock page links to the company’s details.
Quick answers
What is a good P/E ratio?
There is no single good number. It depends on the industry, growth rate and interest rates. Compare to similar companies and to the company’s own past.