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 Social Security Taxes Estimate how much of your Social Security benefit may be considered taxable. What Do Your Taxes Pay For? Here's a breakdown of how the federal government spends your tax money. Federal Income Tax Use this calculator to estimate your income tax liability along with average and marginal tax rates.