The P/E ratio is the price you pay for a stock divided by the earnings the company generates per share. At its core it answers a single question: how many dollars am I paying for each dollar of annual profit?
The formula
P/E = Stock Price ÷ Earnings Per Share (EPS). If a stock trades at $60 and earns $4 per share, its P/E is 15×. Alternatively, P/E = Market Capitalisation ÷ Net Income — the result is identical. Most data sources use trailing twelve months (TTM) EPS by default.
What the number actually tells you
In isolation, P/E tells you almost nothing useful. A P/E of 15 is cheap in one context and expensive in another. What matters is the comparison:
| Context | Why it matters |
|---|---|
| vs the stock's own history | Is the market paying more or less than usual for this specific company's earnings? |
| vs sector peers | Are investors rewarding this business relatively more or less than its competitors? |
| vs growth rate (PEG) | Is a higher P/E justified by a faster growth rate? |
The historical percentile is the most actionable of these three. When a stock's P/E is in the bottom 15% of its 10-year range, the market is paying unusually little for its earnings — regardless of what the S&P 500's average P/E happens to be.
How to read the P/E history chart
The shaded blue band on the chart shows the stock's 25th–75th percentile P/E range over the selected period. The dashed median line is the 50th percentile. When the current P/E line sits below the band, the stock is historically cheap relative to its own earnings history. Above the band: historically expensive.
The coloured zones at the top of the page extend this further — "historically cheap" means the P/E is in approximately the bottom 10–25% of historical readings; "historically pricey" means top 10–25%.
The earnings trap: when low P/E is a mirage
The most important caveat with P/E is cyclicality. For businesses whose earnings swing sharply with the economic cycle — energy producers, materials companies, banks — the P/E can look deceptively low exactly when earnings are at their peak. If oil prices collapse next year, the "E" shrinks dramatically and the historical P/E percentile becomes meaningless.
Graham's solution was normalised earnings: instead of trailing EPS, use the average of 7–10 years of earnings to smooth out cycles. Sixtycents uses the rolling historical range to help you see whether a low P/E is genuinely unusual or just the cyclical pattern repeating.
- For defensive, stable businesses (consumer staples, healthcare): P/E history is highly reliable
- For cyclicals (energy, materials, financials): use EV/EBITDA or normalised earnings instead
- For early-stage/loss-making companies: P/E is meaningless — use EV/Revenue or FCF yield
Common rules of thumb
| P/E level | Rough interpretation (defensive stock) |
|---|---|
| < 12× | Deep value territory — check for structural issues |
| 12–18× | Historically fair to cheap for most blue chips |
| 18–25× | Premium valuation — needs growth to justify |
| > 25× | High expectations baked in — limited margin of safety |
These are starting points, not rules. A Dividend King with 50 years of consecutive growth might always trade between 18–28× — a P/E of 20 would be near the low end of its historical range, not "expensive."
Every stock page on Sixtycents shows the current P/E as a percentile of its own history — with the full chart so you can see the trend, not just the current snapshot.
Check AAPL's P/E history →