WACC (Weighted Average Cost of Capital) is basically the average rate a company pays for its financing from both debt and equity. The formula is: WACC = (E/V × Re) + (D/V × Rd × (1 − Tax Rate)), where E = equity, D = debt, V = total value (E+D), Re = cost of equity, and Rd = cost of debt. In simple terms, you find the proportion of equity and debt, multiply them by their respective costs, adjust debt for tax, and add them up. I usually just plug the numbers into this formula, and it becomes pretty straightforward.