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 Message Thank you! Oops! Related Content How to Read Your Credit Report Solve a mystery while learning how important your credit report is with this story-driven interactive. Social Security Benefits: How Much Will I Receive Calculating your potential Social Security benefit is a three-step process. You May Need to Make Estimated Tax Payments If… Have income that isn’t subject to tax withholding? Or insufficient withholdings? You may have to pay estimated taxes.