P/E ratio = Share price ÷ Earnings per share (EPS)
Use the current market price per share
Use the company’s earnings per share, usually trailing 12 months or forward EPS
If using total earnings, P/E ratio = Market capitalization ÷ Net income
Example: if share price is $50 and EPS is $5, P/E ratio = 10
If EPS is zero or negative, P/E ratio is not meaningful