P/E is a company’s “price to earnings ratio.” Let's say that a company's stock trades for $100 and that the company has earnings per share (EPS) of $6.50 over the last 12 months. We can calculate a trailing ("last 12 months") P/E ratio for that stock by simply dividing the stock price ("P") by the EPS ("E"), so 100/6.50 equals about 15.
