P/E Ratio (Price-to-Earnings)
Use the P/E Ratio (Price-to-Earnings) Calculator → Try the P/E Ratio (Price-to-Earnings) Quiz →The P/E Ratio (Price-to-Earnings) is a stock's price divided by its annual earnings per share. It answers: how many dollars are investors paying for each dollar of profit? A higher P/E reflects higher growth expectations - or higher risk.
- P/E = Stock Price / EPS. A P/E of 25 means you are paying $25 for every $1 of annual earnings. The inverse (1/25 = 4%) is the earnings yield, comparable to bond yields.
- The Shiller CAPE (10-year inflation-adjusted P/E) has historically averaged 16-17 for the S&P 500, providing a long-run baseline for market-level valuation.
- A high P/E requires high future earnings growth to justify - if growth disappoints, multiple compression can cause large stock price declines even when the business remains operationally sound.
- P/E is undefined (not negative) when earnings are negative. For loss-making companies, use Price/Sales, EV/Revenue, or DCF instead.
- EV/EBITDA is preferred over P/E for comparing companies with different leverage because it is capital-structure neutral; P/E is distorted by interest expense and tax differences.
$$\text{P/E} = \frac{\text{Stock Price}}{\text{Earnings Per Share (EPS)}}$$
What is P/E Ratio (Price-to-Earnings)?
The P/E Ratio (Price-to-Earnings) is calculated by dividing a company's current stock price by its Earnings Per Share (EPS). It is the most widely cited equity valuation multiple because it directly answers the investor's most fundamental question: how much am I paying for each dollar of annual profit?
The trailing P/E uses the most recent 12 months of reported EPS (also called LTM - last twelve months). The forward P/E uses consensus analyst estimates for the next 12 months of expected EPS. Forward P/E is typically lower than trailing P/E for growing companies (because earnings are expected to rise) and is the more decision-relevant figure for forward-looking investors.
The inverse of the P/E - EPS divided by Price - is the earnings yield, expressed as a percentage. It makes P/E directly comparable to bond yields. A P/E of 20 implies a 5% earnings yield. If a 10-year government bond yields 4.5%, the equity risk premium is modest. If bonds yield 2%, the equity risk premium is more comfortable.
P/E Ratio (Price-to-Earnings) explained to a beginner
The P/E ratio tells you what the market is currently willing to pay per dollar of earnings. If a company earns $5 per share and the stock trades at $100, the P/E is 20 - you are paying $20 for each $1 of annual profit. If a peer earns the same $5 but trades at $50, its P/E is 10. The higher P/E company is "more expensive" per dollar of earnings.
Why would anyone pay more? Because they expect faster earnings growth. A 20 P/E can be fair if earnings double in 3 years; it is expensive if earnings are flat. This is why a company trading at a P/E of 35 when peers average 15 is not automatically overvalued - it just means investors are betting on faster-than-average growth. The bet may or may not pay off.
When to use P/E Ratio (Price-to-Earnings)
Use P/E as a first-pass relative valuation: compare a company's P/E to its own historical range, to sector peers, and to the broader market index. A company trading at a P/E of 35 when peers average 18 is either higher quality, higher growth - or overvalued. Use forward P/E for growth companies where trailing earnings understate future profit potential.
Worked examples for P/E Ratio (Price-to-Earnings)
This table quickly gives you the overview you need to understand P/E Ratio (Price-to-Earnings) and its most important comparisons.
| Company | Stock Price | EPS (TTM) | Trailing P/E | Earnings Yield | Sector Avg P/E | Relative Premium |
|---|---|---|---|---|---|---|
| Growth Tech | $180 | $4.50 | 40x | 2.5% | 28x | +43% |
| Mature Retail | $45 | $4.50 | 10x | 10% | 12x | −17% |
| Utility | $60 | $4.00 | 15x | 6.7% | 16x | −6% |
| Pharma | $120 | $8.00 | 15x | 6.7% | 18x | −17% |
Common pitfalls
P/E is meaningless for companies with negative earnings and misleading during earnings distortions (one-off charges, litigation settlements). A very low P/E can signal value or a value trap - a business in terminal decline. A high P/E requires high future earnings growth to justify; if growth disappoints, multiple compression can cause significant stock price declines even if the business remains fundamentally sound.
The Shiller CAPE (cyclically adjusted P/E) for the S&P 500 has averaged approximately 16-17 over its full history since 1871, though it has traded well above this level for much of the period since 2010. (Shiller, Yale, 2024)
Frequently asked questions about P/E Ratio (Price-to-Earnings)
What is a fair P/E ratio?
There is no universal fair P/E. The Shiller CAPE (cyclically adjusted P/E, averaging 10 years of real earnings) has historically averaged around 16–17 for the S&P 500, though this has risen significantly since 2010. Growth companies with 20–30% earnings growth can warrant P/Es of 30–50 if the growth materialises. The relevant comparison is always the company's earnings growth rate relative to the P/E - the PEG ratio (P/E divided by growth rate) adjusts for this.
Can P/E be negative?
P/E is undefined - not negative - when EPS is negative because the company has negative earnings. Some systems display a negative P/E in this case, but it is not analytically meaningful. For loss-making companies, analysts typically use Price/Sales, EV/Revenue, or a DCF model instead.
What is the difference between P/E and EV/EBITDA?
P/E is an equity-level metric using share price and per-share earnings - affected by capital structure (leverage) and tax. EV/EBITDA is a firm-level metric using Enterprise Value (equity + debt − cash) and pre-tax, pre-depreciation earnings - making it capital-structure neutral. EV/EBITDA is preferred for comparing companies with different leverage or tax profiles and is the dominant metric in M&A. P/E is easier to understand and more widely reported in public equity markets.
Quiz: how well do you know P/E ratio?
1. What investor question does the P/E ratio directly answer?
2. Why is forward P/E typically lower than trailing P/E for growing companies?
3. From the examples table, which company trades at the largest premium to its sector average P/E?
4. What does a very low P/E potentially signal, according to the pitfalls section?
5. Why is EV/EBITDA preferred over P/E for comparing companies with different levels of leverage?