I'm just seeing this old answer and it is partly incorrect.
The donation value of personal property depends on what the charity will use it for. If the property will be used for a related purpose (a chair to be used as a chair by the charity, a painting to be hung on the wall, etc.) then the donation value is the fair market value.
If the property will be used for an unrelated purpose (unrelated to the nature of the property -- usually this means the property will be sold to raise money for other charitable purposes), then the donation value is your cost basis or the present FMV, whichever is lower.
For most personal property, the cost basis is what you paid for it. For inherited property items only, your cost basis is the FMV on the date of the previous owner's death.
Putting these 3 rules together means that for inherited property only, the donation value will be either the FMV on the date of the donation or the FMV on the date the previous owner died. But for all other personal property (property you bought or was gifted to you) you have to consider the FMV, how the charity will use it, and how much you paid for it originally.
