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. Have A Question About This Topic? Name Email Address Question Thank you! Oops! Related Content Social Security Taxes Estimate how much of your Social Security benefit may be considered taxable. Should You Ever Retire? A growing number of Americans are pushing back the age at which they plan to retire. Or deciding not to retire at all. Self-Employed Retirement Plans Estimate the maximum contribution amount for a Self-Employed 401(k), SIMPLE IRA, or SEP.