See who's highest and who's lowest. An average IQ is around 100. Did higher IQs yield greater achievements? We include information about each prez's smart or not-so-smart decisions.

Presidents Barack Obama and Donald Trump aren't part of the ranking — they came along after the IQ research was conducted.

1. (Highest) John Quincy Adams

President John Quincy Adams
Wikimedia Commons / Public Domain

IQ score: 168.75

While studying law at Harvard University, America's future sixth president (1825-1829) became romantically involved with a local woman, but his parents advised him to establish his career before marrying her.

Brokenhearted or not, Adams listened to the advice — and went on to become one of the most respected and productive presidents ever.

He's remembered for his diplomatic skills: he settled the Treaty of Ghent and ended the War of 1812; negotiated with Britain over the location of the U.S. border with Canada; and purchased Florida from Spain.

His successes sure make a good case for choosing duty over love…

2. Thomas Jefferson

President Thomas Jefferson. Official presidential portrait by Rembrandt Peale
Wikimedia Commons / Public Domain

IQ score: 153.75

Officially, Thomas Jefferson was a planter, lawyer and politician — but he also had in-depth knowledge of mechanics, several languages and architecture, and he was a talented surveyor and mathematician.

He was an extremely busy man with a huge range of interests that he kept under control with a very strict schedule: He rose with the sun, ate breakfast strictly at 8, had a big lunch at 3, and kept track of everything in a trusty notebook.

Jefferson's achievements include writing the Declaration of Independence when he was in his early 30s.

As the third president (1801-1809), he: doubled the country’s territory; negotiated peace with France; and developed American trade. He remained an overachiever after retiring from office, when he founded the University of Virginia.