Tax Withholding Estimator for the Self-employed?

The IRS says its online Tax Withholding Estimator tool can be used by self-employed individuals to estimate their tax. The tool has the ability to factor in the self-employed health insurance deduction and the deduction for contributions to a SEP or other qualified retirement plan. The estimator automatically calculates the self-employment tax and the self-employment tax deduction and incorporates these into its overall tax liability estimate.