A "good" price-to-earnings (P/E) ratio varies significantly depending on the specific industry sector, the company's growth rate, and broader macroeconomic conditions. While a historical rule of thumb often viewed a P/E between 15 and 20 as fair value for a mature company, high-growth technology firms frequently command much higher multiples, whereas capital-intensive or cyclical industries trade at lower ratios. Investors evaluate a company's P/E relative to its historical averages, peer group performance, and projected future earnings growth rather than relying on a universal fixed number.