Capital Gains Tax Estimator Use this calculator to estimate your capital gains tax. You are viewing this website at a small screen resolution which doesn't support calculators. Click here to view this calculator. Share | Related Content Comparing Investments This calculator compares the net gain of a taxable investment versus a tax-favored one. How Income Taxes Work A quick look at how federal income taxes work. Federal Income Tax Use this calculator to estimate your income tax liability along with average and marginal tax rates.