The names who made the list may seem surprising, especially compared to other rankings of philanthropy. While the Chronicle of Philanthropy creates a list of the 50 largest donors any given year, this list in particular uses relative generosity as its main criteria.
12. Michael Dell
The Michael and Susan Dell Foundation has given away nearly $1 billion since 2000, equal to about 10% of their estimated net worth of $17.5 billion.
11. Paul Allen
The Microsoft co-founder gave away $327.6 million in 2011, making him the most generous American of that year. He's given away just over $1.5 billion of the estimated $16 billion he's worth.
AP Photo/Paul Sakuma
Mark Zuckerberg
10. Mark Zuckerberg
AP Photo/Paul Sakuma
Mark Zuckerberg
The 29-year-old's $992-million gift was the single biggest donation of 2013. He's donated about $2 billion of his wealth, which is now estimated to be $28.5 billion.
9. Pierre Omidyar
E-bay founder Pierre Omidyar and his wife Pam have given away more than $1 billion, donating $225 million in 2013 alone.
8. David Bohnett
Bohnett made $300 million when he sold GeoCities to Yahoo! in 1998. Since then, his foundation has given away nearly $53.5 million to charitable causes, with a special focus on the LGBT community.
7. Irwin Jacobs
The Qualcomm founder and his wife Joan have been very generous over the past few decades, donating around $500 million of their fortune, estimated at $1.8 billion.
pmo via Flickr
Jeff Skoll and Pierre Omidyar
6. Jeff Skoll
pmo via Flickr
Jeff Skoll and Pierre Omidyar
When eBay's first president signed the Giving Pledge, he said he hoped to donate nearly all of his $3.8 billion "to the betterment of humanity."
5. Tim Gill
Gill made about $500 million when he sold Quark at the height of the dotcom boom. His foundation has given about $240 million towards LGBT initiatives.
4. Ed Scott
Scott, who made his fortune with a software company called BEA, isn't at the Forbes 400 level, but Inside Philanthropy describes him as "Silicon Valley's most effective global giver." His donations have gone towards fighting global poverty and disease, as well as projects to find better treatments for autism.
3. Bill Gates
Gates has donated more money than any other living person, but he wasn't first on Inside Philanthropy's list because his current net worth is $76 billion, nearly twice the endowment of the Bill and Melinda Gates Foundation.
2. Gordon Moore
Intel co-founder Gordon Moore and his wife Betty put about half of their wealth into their foundation in 2011. It has since made about $3 billion in grants, focused mostly on scientific research and Bay Area charities.
Neilson Barnard/Getty Images
Sandy Lerner
1. Leonard Bosack and Sandy Lerner
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Sandy Lerner
The Cisco co-founders have given more than anyone else, relative to their total wealth. They made $170 million when they walked away from their company in 1990, but they gave about 70% of that money away to charity.
The Least Generous Tech Leaders
Inside Philanthropy also compiled a list of the least generous people in tech. Though these executives have made valuable contributions to charity in the past, IP argues that these six people have donated the least amount of money compared to their total amassed wealth.
Among the biggest offenders are (not ranked): Jeff Bezos, Larry Page, Steve Ballmer, Larry Ellison, Jerry Yang, and Michael Birch.