How to Calculate the P/E Ratio
Formula: Share Price ÷ Earnings Per Share (EPS)
Example: share price $100, annual EPS $10 → P/E = 10. Investors are paying $10 for every $1 of annual earnings. At current profitability, payback takes 10 years.
Forward P/E uses projected next-year earnings instead of trailing EPS — more forward-looking but dependent on the accuracy of analyst forecasts.
How to Interpret the P/E Ratio
Low P/E: May indicate undervaluation — or low growth expectations or elevated risk. Context is everything.
High P/E: Reflects high growth expectations. If those expectations are not met, the stock can fall sharply.
Never interpret P/E in isolation. Compare it to sector peers, the company's own historical range and its expected growth rate.
Sector P/E Benchmarks
Technology companies typically trade at 20–40+ P/E due to high growth expectations. Banks and energy companies often trade at 6–12 P/E.
Use sector-specific benchmarks rather than a universal "good P/E" — a P/E of 25 could be cheap for a high-growth tech company but expensive for a utility.