Weighted average cost of capital (WACC) is a calculation of a company's cost of capital, or the minimum that a company must earn to satisfy all debts and support all assets. The calculation includes the company's debt and equity ratios, as well as all longterm debt. Companies usually do an internal WACC calculation to assess overall company health. The larger and more complex a company is, the harder it is to determine WACC. Unfortunately, only some of the information needed to calculate WACC can be found on a balance sheet.
Calculating WACC

Gather the required information from the balance sheet. Finding the information is the hardest step. Write out the full WACC equation and list the variables separately. It is a good idea to make a list of all your variables before rewriting the equation.
WACC = [(E/V) Re] + [(D/V) Rd * (1Tc)]
Re= cost of equity (expected rate of return on equity)
Rd = cost of debt (expected rate of return on debt)
E = market value of company equity
D = market value of company debt
V = total capital invested, which equals E + D
E/V = percentage of financing that is equity
D/V = percentage of financing that is debt
Tc = corporate tax rate 
Start calculating the variables. Start with cost of equity and cost of debt. Some companies include these ratios on the balance sheet or income statement. It is a good idea to check both those reports and the executive summary at the beginning of financial statementswhy do calculations if the company has done them for you?
Cost of equity
Re = (next year's dividends per share/current market value of stock) + growth rate of dividends
If next year's dividends are not provided, you can either guess or use current dividends. Current market value of stock will be included in a company's financial reports, but also can be found at nasdaq.com.
Aftertax cost of debt
Rd = yield to maturity of outstanding debt as a percentage * (1  tax bracket)
All these variables can be found in the balance sheet, income statement or annual financial reports for a publicly traded company. 
Find current market values for equity (E) and debt (D). This is not the same as the owner's equity listed on the balance sheet. Owner's equity is book, or historical, value. Many companies include market value statistics in their financial reports, but you usually will not find it on the balance sheet. Go to sec.gov to look up annual filings of public companies or ask for full financial reports.

Calculate total equity by adding E + D.

Look up the corporate tax rate. The effective tax rate listed on the income statement will tell you what taxes were charged. This is fine for a shortterm analysis, but if you are thinking longterm, you will need to estimate the marginal tax rate for the future.

Plug all the values you found into the equation. Solve for WACC.
Tips & Warnings
 On the balance sheet and income statement, circle the numbers you used so you can find them again easily.
 This equation does not take preferred stock into account.