Reading stocks
What Is the P/E Ratio? Price-to-Earnings Explained Simply
How to calculate the price-to-earnings ratio, what a high or low P/E can mean, and the mistakes beginners make when using it.
Beginner investing lessons and fake-money practice from the maker of Quoliv.
Quick answer
The P/E ratio is a company's share price divided by its earnings per share. It shows how many dollars investors are paying for each dollar of yearly profit. A share at $50 with earnings of $2.50 per share has a P/E of 20. A high or low P/E is a starting point for questions, not a buy or sell signal.
What you’ll learn
- P/E = share price ÷ earnings per share (EPS).
- It shows what investors pay for each unit of profit.
- A high P/E often reflects expectations of growth; a low P/E can mean pessimism or problems.
- Compare P/Es within the same industry, not across very different businesses.
- Companies with no profit don't have a meaningful P/E.
This explanation is part of our Stocks lessons path, where you can explore the idea in short lessons and quizzes.
The formula
P/E ratio = share price ÷ earnings per share. Earnings per share is the company's profit divided by its number of shares.
Example: a company earns $100 million and has 40 million shares, so EPS is $2.50. If the share price is $50, the P/E is 50 ÷ 2.50 = 20. Investors are paying $20 for every $1 of yearly profit.
Trailing vs forward P/E
| Trailing P/E | Forward P/E | |
|---|---|---|
| Uses | Profit from the last 12 months | Analysts' forecast for the next 12 months |
| Strength | Based on real results | Looks ahead |
| Weakness | Backward looking | Forecasts can be wrong |
What high and low P/E can mean
A high P/E usually means investors expect profits to grow quickly, so they're willing to pay more today. If that growth doesn't arrive, the price can fall hard.
A low P/E can mean a company is overlooked—or that investors expect its profits to shrink. Sometimes a stock looks cheap for a good reason.
P/E tells you what the market expects. It doesn't tell you whether the market is right.
Common beginner mistakes
- Comparing a fast-growing tech company's P/E with a utility's—different businesses have different normal ranges.
- Treating a low P/E as an automatic bargain.
- Ignoring one-off events that make a single year's profit unusually high or low.
- Forgetting that loss-making companies have no useful P/E at all.
Sources and methodology
This guide was written for education using the primary sources below. It does not evaluate your finances or recommend an investment. Read our editorial policy.