The Zakat Foundation of America offers our own zakat calculator to help you determine how much zakat you need to pay. The zakat calculator considers your comprehensive net assets (total wealth). Remember that charity in Islam (Zakat) is not just one of the core pillars of Islam, but a tool to help ease poverty, suffering and hardship throughout the globe.
Your donations are tax exempt under the section 170 of the 501(c)(3) section of the IRS code.
Zakat Foundation of America Tax EIN: 36-4476244
For more information on tax exempt status please refer to this letter.