What Is the P/E Ratio?
The Price-to-Earnings (P/E) ratio is the most widely used valuation metric in investing. It answers a simple question: how much are investors paying per dollar of earnings?
P/E Ratio = Share Price ÷ Earnings Per Share (EPS)
Example:
- Stock price: $100
- Earnings per share (EPS): $5
- P/E = $100 ÷ $5 = 20
A P/E of 20 means investors pay $20 for every $1 the company earns annually.
In PaperTrade Academy: The stock quote panel displays the P/E ratio. Compare it to peers and the market average when evaluating a position.
Trailing vs. Forward P/E
| Type | Earnings used | What it tells you |
|---|---|---|
| Trailing P/E (TTM) | Last 12 months of actual reported earnings | Historical valuation based on real results |
| Forward P/E | Next 12 months of analyst earnings estimates | Valuation based on expectations (can be wrong) |
When analysts expect strong earnings growth, forward P/E is typically lower than trailing P/E. When analysts expect a decline, forward P/E is higher.
What Is a "High" or "Low" P/E?
Context is everything. There is no universal "fair" P/E — it depends on:
- Growth rate — high-growth companies command higher P/Es because future earnings will be much larger
- Industry — technology and biotech traditionally trade at higher P/Es than utilities and banks
- Interest rates — when rates are low, investors accept lower earnings yields → higher P/Es are supported
- Market cycle — the S&P 500's average P/E has ranged from ~10 (recessions) to ~35+ (bull markets)
Rough historical context:
| P/E range | Interpretation |
|---|---|
| Below 10 | Potentially cheap — or earnings problems ahead |
| 10–20 | Moderate — fair value for many large-cap companies |
| 20–35 | Growth premium priced in |
| Above 35 | Very high expectations — any miss can be punishing |
Always Compare Apples to Apples
Comparing P/E ratios across sectors is misleading:
- Utility company at P/E 16 → looks fairly valued (utilities average ~14–18)
- Tech company at P/E 16 → looks cheap (tech often trades 25–40)
Always compare P/E to: