What financial metric is most commonly used to indicate a company's profitability?

The financial metric most commonly used to indicate a company's profitability is the net profit margin. This metric measures the percentage of revenue that remains as profit after all expenses are accounted for, including operating costs, interest, taxes, and others. A higher net profit margin indicates a more profitable company, as it demonstrates the ability to convert revenue into actual profit efficiently.

In comparison, return on investment (ROI) is a measure of the gain or loss generated relative to the investment cost, which can provide insights into the efficiency of an investment rather than overall profitability. Free cash flow is focused on the cash a company generates after accounting for capital expenditures, which is important for understanding liquidity rather than direct profitability. Operating income reflects profit from core business operations, excluding other revenues and expenses, but does not encompass all factors influencing the final profitability. Therefore, the net profit margin is widely recognized as a key indicator of a company's overall profitability.