Short answer: Presidential IQ rankings rest on estimates, not test results. The standard scholarly source is psychologist Dean Keith Simonton's 2006 study in Political Psychology, which covered 42 presidents from George Washington to George W. Bush. On his corrected early-adult measure, John Quincy Adams ranks first at 175, Thomas Jefferson and James Madison tie at 160, and Ulysses S. Grant ranks last at 130. Presidents after Bush fall outside the study.
At a glance
| Study | Dean Keith Simonton, "Presidential IQ, Openness, Intellectual Brilliance, and Leadership," Political Psychology 27(4), 2006, pp. 511–526 |
|---|---|
| Presidents covered | 42, from George Washington to George W. Bush |
| Highest estimate | John Quincy Adams, 175 |
| Lowest estimate | Ulysses S. Grant, 130 |
| Rated from historical records | 8 presidents, using Catharine Cox's 1926 figures |
| Estimated statistically | 34 presidents, imputed from intellectual-brilliance and openness ratings |
| Presidents after 2006 | No estimate in the study; this site publishes none for serving politicians |
How the List Was Built
None of the figures on this page is a test score. Every one is a reconstruction. Dean Keith Simonton, a psychologist at the University of California, Davis, assembled it in 2006 from three earlier bodies of work.
- Catharine Cox (1926). In The Early Mental Traits of Three Hundred Geniuses, Cox dated each subject's childhood and adolescent achievements and compared them with population norms. Eight presidents made her sample: Washington, John Adams, Jefferson, Madison, John Quincy Adams, Jackson, Lincoln and Grant.
- Intellectual Brilliance. Simonton's own 1986 ratings, covering 39 presidents, built from anonymized biographical profiles.
- Openness to Experience. Scores for 32 presidents from Steven Rubenzer and Thomas Faschingbauer's 2004 expert-rater study.
Simonton then filled the gaps with the expectation-maximization algorithm, a standard method for estimating missing values from the values that exist. The output is four IQ estimates per president: childhood and early adulthood, each uncorrected and corrected for the reliability of the data.
Selection criteria for this ranking: every president in Simonton's Table 1, ordered by the corrected early-adult estimate (column II-C). That column drew most of the press coverage in 2006, and it is the figure most often quoted since. Ties share a rank. For how the Cox method works and where it fails, read historical IQ estimates explained.
The Full Ranking, 1 to 42
The table gives each president's corrected early-adult figure, the spread across all four of Simonton's estimates, and whether the number traces to Cox's historical ratings or to Simonton's statistical imputation.
| Rank | President | Simonton estimate | Range, all four estimates | Basis |
|---|---|---|---|---|
| 1 | John Quincy Adams | 175 | 165–175 | Cox (1926) historical ratings |
| 2 | Thomas Jefferson | 160 | 145–160 | Cox (1926) historical ratings |
| 2 | James Madison | 160 | 120–160 | Cox (1926) historical ratings |
| 4 | John F. Kennedy | 159.8 | 138.9–159.8 | Imputed from brilliance and openness ratings |
| 5 | Bill Clinton | 159 | 135.6–159 | Imputed from brilliance and openness ratings |
| 6 | Jimmy Carter | 156.8 | 130.2–156.8 | Imputed from brilliance and openness ratings |
| 7 | Woodrow Wilson | 155.2 | 133–155.2 | Imputed from brilliance and openness ratings |
| 8 | John Adams | 155 | 120–155 | Cox (1926) historical ratings |
| 9 | Theodore Roosevelt | 153 | 129.7–153 | Imputed from brilliance and openness ratings |
| 10 | James A. Garfield | 152.3 | 129–152.3 | Imputed from brilliance and openness ratings |
| 10 | Chester A. Arthur | 152.3 | 129–152.3 | Imputed from brilliance and openness ratings |
| 12 | Franklin D. Roosevelt | 150.5 | 127.4–150.5 | Imputed from brilliance and openness ratings |
| 13 | Abraham Lincoln | 150 | 125–150 | Cox (1926) historical ratings |
| 14 | Millard Fillmore | 149 | 120.8–149 | Imputed from brilliance and openness ratings |
| 15 | John Tyler | 148.1 | 122.9–148.1 | Imputed from brilliance and openness ratings |
| 16 | Franklin Pierce | 147.4 | 120.6–147.4 | Imputed from brilliance and openness ratings |
| 17 | William Henry Harrison | 146.3 | 120.3–146.3 | Imputed from brilliance and openness ratings |
| 17 | Rutherford B. Hayes | 146.3 | 120.3–146.3 | Imputed from brilliance and openness ratings |
| 19 | Martin Van Buren | 146 | 119.4–146 | Imputed from brilliance and openness ratings |
| 20 | Benjamin Harrison | 145.4 | 117.5–145.4 | Imputed from brilliance and openness ratings |
| 21 | Dwight D. Eisenhower | 145.1 | 117.3–145.1 | Imputed from brilliance and openness ratings |
| 22 | Andrew Jackson | 145 | 110–145 | Cox (1926) historical ratings |
| 23 | Grover Cleveland | 144 | 116.9–144 | Imputed from brilliance and openness ratings |
| 24 | James K. Polk | 143.4 | 116–143.4 | Imputed from brilliance and openness ratings |
| 24 | William McKinley | 143.4 | 116–143.4 | Imputed from brilliance and openness ratings |
| 26 | George H. W. Bush | 143 | 116.5–143 | Imputed from brilliance and openness ratings |
| 27 | Richard Nixon | 142.9 | 118.9–142.9 | Imputed from brilliance and openness ratings |
| 28 | Ronald Reagan | 141.9 | 118–141.9 | Imputed from brilliance and openness ratings |
| 29 | Calvin Coolidge | 141.6 | 111.4–141.6 | Imputed from brilliance and openness ratings |
| 29 | Herbert Hoover | 141.6 | 118–141.6 | Imputed from brilliance and openness ratings |
| 31 | Lyndon B. Johnson | 140.6 | 114.8–140.6 | Imputed from brilliance and openness ratings |
| 32 | Gerald Ford | 140.4 | 113.3–140.4 | Imputed from brilliance and openness ratings |
| 33 | George Washington | 140 | 125–140 | Cox (1926) historical ratings |
| 34 | Warren G. Harding | 139.9 | 107.8–139.9 | Imputed from brilliance and openness ratings |
| 35 | Zachary Taylor | 139.8 | 110.8–139.8 | Imputed from brilliance and openness ratings |
| 35 | Andrew Johnson | 139.8 | 110.8–139.8 | Imputed from brilliance and openness ratings |
| 35 | Harry S. Truman | 139.8 | 115.5–139.8 | Imputed from brilliance and openness ratings |
| 38 | James Buchanan | 139.6 | 111.9–139.6 | Imputed from brilliance and openness ratings |
| 39 | William Howard Taft | 139.5 | 114.5–139.5 | Imputed from brilliance and openness ratings |
| 40 | James Monroe | 138.6 | 109–138.6 | Imputed from brilliance and openness ratings |
| 41 | George W. Bush | 138.5 | 111.1–138.5 | Imputed from brilliance and openness ratings |
| 42 | Ulysses S. Grant | 130 | 110–130 | Cox (1926) historical ratings |
Every corrected early-adult figure sits at or above 130, the traditional Mensa threshold on a standard-deviation-15 scale. See what an IQ of 130 means and the IQ rarity chart for how uncommon these numbers would be in a general population.
The Top Tier: Adams, Jefferson, Madison
John Quincy Adams leads on all four measures, from 165 in childhood to 175 corrected. Cox gave him the highest figures of any president in her sample. He went on to teach rhetoric at Harvard and kept a diary for most of his life.
Jefferson and Madison tie at 160. Jefferson also holds the highest Intellectual Brilliance rating, 3.1, and the highest Openness score, 99.1, of any president in the table. His case is examined in detail in Thomas Jefferson's IQ.
The next two places belong to John F. Kennedy at 159.8 and Bill Clinton at 159.0 in Simonton's estimates. Neither appears in Cox, so both numbers are imputed. Each received an Openness score of 82.0, and Kennedy's Intellectual Brilliance rating of 1.8 is second only to Jefferson's. Jimmy Carter, at 156.8, shows how heavily the model leans on Openness: his brilliance rating is 0.0, but his Openness score of 77.0 lifts him to sixth.
The Bottom of the Table
Ulysses S. Grant ranks last at 130. His figure comes from Cox's historical ratings, not from imputation. Simonton's estimates place George W. Bush 41st at 138.5, just below James Monroe at 138.6 and William Howard Taft at 139.5.
George Washington, at 140, ranks 33rd. His Openness score is 14.0, against Jefferson's 99.1, and his schooling ended in his teens. His full record is in George Washington's IQ. Abraham Lincoln, with almost no formal schooling, still reaches 150 on Cox's data; see Abraham Lincoln's IQ.
The spread between the 2nd and the 41st president on this measure is 21.5 points. On the childhood measure the range widens: from 107.8 for Warren G. Harding to 165 for John Quincy Adams.
What Simonton Was Testing
The rankings were a means, not the goal. Simonton wanted to know whether intellect predicts how historians rate a president's performance. He correlated his IQ estimates with published leadership ratings. The Wilson Quarterly's report on the study paraphrased his view that intellect is not the only predictor of good leadership, and quoted him calling his conclusion tentative.
The study's abstract states its scope precisely: "IQ scores were estimated for all 42 chief executives from George Washington to G. W Bush." The 42 counts Grover Cleveland once, though he served two nonconsecutive terms.
The Limits of the Method
Thirty-four of the 42 figures are statistical inferences from expert ratings, not readings of documents. Two rows make the point. James A. Garfield and Chester A. Arthur have identical inputs, a brilliance rating of 0.9 and an Openness score of 52.9, and so receive identical estimates on all four measures, down to the decimal. William Henry Harrison and Rutherford B. Hayes match the same way. The model cannot tell apart men whose ratings match.
The decimals themselves imply false precision. A single modern IQ score carries a confidence interval of roughly five points either way; a retrospective estimate carries more. Read 159.8 and 159.0 as the same band.
Historians objected at the time. Writing for the History News Network on November 6, 2006, the Kennedy biographer Thomas C. Reeves argued the study "has little if any value," faulting its reliance on biographies rather than primary sources. The fair reading: the ranking orders presidents by how intellectually open and brilliant experts judged them to be, translated onto an IQ scale.
Obama, Trump and Biden: Outside the Study
Simonton's data end with George W. Bush. Barack Obama, Donald Trump, Joe Biden and Donald Trump again in his current term, which began on January 20, 2025, are not in the study, and no comparable peer-reviewed estimate has been published for them. Geniuses.club gives no IQ estimate for serving politicians, and it does not repeat unsourced figures for any recent president.
Viral numbers have a poor record. In 2001 an email attributed presidential IQ scores from Franklin D. Roosevelt to George W. Bush to a "Lovenstein Institute" that did not exist. The Guardian printed the figures in a diary column on July 19, 2001, and retracted them two days later. The hoax resurfaced in Spanish-language media in 2007. Any presidential IQ figure without a named author, method and publication belongs in that category.
Where to Go Next
The founders also appear in the wider Cox sample: see Alexander Hamilton's IQ and Benjamin Franklin's IQ. For the scale behind every number on this page, read what counts as a high IQ, and browse every guide in IQ guides. To measure your own reasoning, take the free practice IQ test; it is a screener, not a clinical assessment.
Frequently asked questions
Which US president had the highest IQ?
In Dean Keith Simonton's 2006 study, John Quincy Adams ranks highest on all four estimates, reaching 175 on the corrected early-adult measure. His figure comes from Catharine Cox's 1926 study of 301 historical geniuses, which rated his documented childhood and youthful achievements. Thomas Jefferson and James Madison tie for second at 160.
Which president had the lowest estimated IQ?
Ulysses S. Grant ranks last in Simonton's table at 130 on the corrected early-adult measure, a figure drawn from Cox's 1926 ratings. That number still sits near the 98th percentile of the general population, so the lowest score in the table is well above average.
Are these real IQ test scores?
No. They are retrospective estimates. Eight come from Catharine Cox's ratings of historical records; the other 34 were imputed statistically from expert ratings of intellectual brilliance and openness to experience. Treat each figure as a band several points wide, not an exact score.
What IQ estimates exist for Obama, Trump and Biden?
None from Simonton's study, which ends with George W. Bush in 2006. No comparable peer-reviewed estimate has been published for later presidents. Geniuses.club gives no IQ estimate for serving politicians and does not repeat the unsourced figures that circulate online.
Was the 2001 presidential IQ list real?
No. The 2001 email crediting a "Lovenstein Institute" with presidential IQ scores was a hoax; the institute did not exist. The Guardian printed it on July 19, 2001, and retracted it two days later. Simonton's 2006 study is unrelated to it.
Sources
- Simonton (2006), Presidential IQ, Openness, Intellectual Brilliance, and Leadership, full-text PDF — Table 1: all four IQ estimates, brilliance and openness scores for 42 presidents; method
- Simonton (2006), Political Psychology 27(4), journal record — Citation of the study
- Wilson Quarterly, Smart and Smarter — Secondary report quoting Adams 175, Jefferson and Madison 160, Kennedy 159.8, Clinton 159, Grant 130; tentative conclusion
- History News Network, Thomas C. Reeves on presidential IQ (Nov. 6, 2006) — Secondary report of the corrected early-adult figures and a historian's critique
- Reader's Digest, The brains of a president — Secondary source quoting Carter 156.8, Wilson 155.2, Garfield and Arthur 152.3, FDR 150.5
- Wikipedia: U.S. presidential IQ hoax — The 2001 Lovenstein Institute hoax, the Guardian retraction, the 2007 revival
- Catharine Cox, The Early Mental Traits of Three Hundred Geniuses (1926), full text — The original source of the eight Cox-rated presidents
Editorial standard: IQ figures for historical figures are retrospective estimates and are labeled as such; scores for living people appear only when the person disclosed them or a reputable outlet reported them. Corrections: contact the editors.