10 Most Generous Rich Americans

While it may not seem like it, some of America's wealthiest people are also the most generous. Every year, businessmen like Bill Gates and Michael Bloomberg make billions of dollars in charitable donations to support a variety of causes ranging from environmental issues to health care.

Business Insider and Wealth X calculated the generosity index of some of the world's biggest philanthropists based on their net worth and lifetime donations amount. Based on their results, here are the 10 of the most generous Americans:

10. Mark Zuckerberg

Company: Facebook

Generosity Index: 4%

Digitiser 2000

The Facebook founder and self-made billionaire joined Giving Pledge, a commitment by the world's richest individuals to donate the majority of their wealth. Zuckerberg has made about $1.6 billion in lifetime donations, including $25 million towards the fight against Ebola, $75 million to San Francisco General Hospital, $120 million to Bay Area schools and $100 million worth of Facebook stocks to one of the New Jersey public school systems.

9. Michael Dell

Company: Dell

Generosity Index: 6%

The Telegraph

Michael Dell is the current CEO and chairman of Dell, one of the world's largest computer technology companies. Dell is the director of the Michael and Susan Dell Foundation which donates to causes related to education, community development and arts. In 2015, he assisted in building a new teaching hospital in Austin, Texas by donating $25 million. It is estimated that he has donated over $1.1 billion of his $18.9 billion net worth.

8. Michael Bloomberg

Company: Bloomberg Media

Generosity Index: 8%

ABC News

The founder and CEO of Bloomberg media company lives by the 'you give what you can' philosophy. His first charitable donation was a $5 check to his college's alumni association, then the rest was history. He has since given over $3 billion in lifetime donations through the Bloomberg Foundation, which supports education, health care and environmental causes.

7. Paul Allen

Company: Microsoft

Generosity Index: 12%

Forbes

Just like his former partner Bill Gates, Microsoft co-founder Paul Allen is very generous. He's the chairman of the Paul G. Allen Family Foundation and has donated billions in his lifetime to healthcare and animal causes. His notable contributions include $7 million in grants to Alzheimer's research, $5 million to Seattle BioMed and $4 million to Global FinPrint, a conservation project for the preservation of sharks.

6. Pierre Omidyar

Company: Ebay

Generosity Index: 16%

Huffington Post

Omidyar is the co-founder and chairman of eBay. The Paris-born Iranian-American businessman started the Omidyar Foundation which includes the Omidyar Network, HopeLab, Humanity United, and Ulupono Initiative. The foundation supports many causes including human rights, hunger relief and entrepreneurship. Omidyar is worth $6.2 billion and has donated over $1 billion to charity.

These wealthy individuals have donated billions and they still haven't cracked the top 5 of the generosity index.

5. Bill Gates

Company: Microsoft

Generosity Index: 32%

BOOMSbeat

The Microsoft co-founder is probably one of the world's most recognizable philanthropists. Along with his wife, Melinda, Gates co-founded the Bill & Melinda Gates Foundation, the largest philanthropic organization in the world. The tech tycoon is also part of Giving Pledge and has already made over $27 billion in lifetime donations. He recently made a $4.6 billion donation on behalf of the foundation, his biggest gift since 2000.

4.Warren Buffett

Company: Berkshire Hathaway

Generosity Index: 35%

Huffington Post

Buffett is one of the wealthiest and most charitable people in the world. As the CEO of Berkshire Hathaway, Buffett pledged to donate 85% of his wealth to charities like the Buffett Family Foundations and Bill & Melinda Gates Foundation. Over the last decade, the billionaire has given away much of his $61 billion net worth to total a lifetime donation of $21.5 billion.

3. Ted Turner

Company: AOL and TBS

Generosity Index: 57%

CNN

The founder of CNN has made $1.2 billion in lifetime donations that total over half of his net worth. He's funded a variety of conservation and environmental causes including giving $17 million to the League of Conservation Voters and creating the Turner Global Foundation. Turner pledged $1 billion to the United Nations Foundation to help causes related to children and women's health, world peace and security.

2. Gordon Moore

Company: Intel

Generosity Index: 77%

Digital Trends

The co-founder of the international tech company Intel Corporation is also a philanthropist who gave away over $5 billion in charitable donations for diverse causes through the Gordon and Betty Moore Foundation. He has also funded a variety of projects relating to space technology and infrastructure.

1. Charles Francis Feeney

Company: Duty Free Shoppers Group

Generosity Index: 420,000%

GoTopTens

Landing in the top spot is Irish American tycoon Charles "Chuck" Feeney. The generous businessman is not only the genius behind the concept of duty-free shopping, he's also the founder of The Atlantic Philanthropies, one of the largest charitable foundations in the world. Although his net worth is sitting at just $1.5 million, Chuck has made a lifetime donation of $6.3 billion dollars, making him the most generous of them all.