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? Name Email Address Question Thank you! Oops! Related Contents The Facts About Income Tax Millions faithfully file their 1040 forms each April. But some things about federal income taxes may surprise you. Tax Deductions You Won't Believe Here are some examples of deductions from the IRS that were permitted and some that were, uh, too creative. Comparing Investments This calculator compares the net gain of a taxable investment versus a tax-favored one.