TurboTax will help you estimate the value of your donated items.
If you're using ItsDeductible, a free TurboTax online tool which lets you track your charitable contributions, you'll be given IRS-approved values for your donations. You may import your donations from ItsDeductible into TurboTax when you prepare your tax return.
The TurboTax program itself can help determine the value of donations that you enter directly. Just be sure to choose the Guide me option when entering the donations. As you continue through the program, you'll enter your donations in a table that includes acceptable values for the items. For example, in the sample screenshot below a person has entered three flannel shirts that were donated to a charitable organization. (Click the screenshot to enlarge it.)
For more information, please see the TurboTax Tax Tip How to Estimate the Value of Clothing for IRS Deductions.