Several key metrics can help entrepreneurs measure profitability: - Gross Profit Margin: The difference between revenue and cost of goods sold. - Net Profit Margin: The percentage of revenue remaining after all expenses are deducted. - Return on Investment (ROI): The gain from an investment relative to its cost. - Earnings Before Interest, Taxes, Depreciation, and Amortization (EBITDA): A measure of a company's overall financial performance.