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 | Have A Question About This Topic? Address Thank you! Oops! Related Contents Federal Income Tax Use this calculator to estimate your income tax liability along with average and marginal tax rates. What If You Get Audited? The chances of an IRS audit aren't that high. And being audited does not necessarily imply that the IRS suspects wrongdoing. Comparing Investments This calculator compares the net gain of a taxable investment versus a tax-favored one.