An EBIT Margin is the operating earnings over operating sales. This margin allows investors to understand true business costs of running a company, because parts of a company's property, plant, and equipment will eventually need to be replaced as they get used, broken down, decayed, etc.
Lower EBIT Margins indicate lower profitability from a company. When comparing against its competitors, investors can determine if lower EBIT margins are due to the competitive landscape (where all companies are having lower margins) or a issue just within the company (where the company is facing lower sales and higher costs).
EBIT Margin (Quarterly) = (operating earnings) / (quarterly sales)
EBIT Margin (TTM) = (last four quarters of operating earnings) / (last four quarters of sales)