[adventured]

Gates is richer than Rockefeller was, by a factor of upwards of two. So yeah, he's definitely among the richest in world history. He's also easily the richest private citizen (non-government, non-military) in history.

Rockefeller's wealth peaked at between $1 and $2 billion, according to the best records on him, including his biographies and records from the Rockefeller Archives. Inflation adjusting those numbers based on the 1890-1910 time frame in which the dollar was extremely stable for the most part, you get between $20 (20x$1b) and $60 (30x$2b) billion, depending on if you want to use the low ball on his wealth plus a low ball on the inflation adjustment vs the opposite end of the spectrum.

[doughj3]

Forbes has estimated Rockefeller's wealth at greater than 300 billion dollars (adjusted to 2006).

http://www.businessinsider.com/richest-people-in-history-201...

[tomhigg]

Better explanation: "John D. Rockefeller, who became the world’s first billionaire in 1916, a sum equal to $30 billion today, adjusted for inflation. In a sense, this underestimates the oil scion’s wealth. By the time Rockefeller died in 1937, his assets equaled 1.5% of America’s total economic output. To control an equivalent share today would require a net worth of about $340 billion dollars, more than four times that of Bill Gates, currently the world’s richest man." http://www.forbes.com/sites/carlodonnell/2014/07/11/the-rock...