William James Sidis IQ

Unknown. The 250 to 300 comes from his sister Helena's claim that his IQ was between those numbers. No test, date or examiner is named, and scholars note the family's habit of exaggeration. A 254 sometimes cited was probably a civil service ranking.

He enrolled at 11 in 1909 and gave a lecture on four-dimensional bodies to the Harvard Mathematical Club in 1910. He graduated cum laude in 1914, aged 16, and then taught mathematics at the Rice Institute in Texas for a year.

He was arrested at a 1919 May Day socialist parade and sentenced to 18 months, then withdrew from public life. He worked clerical jobs, wrote under pseudonyms and sued The New Yorker in 1937 over a profile, settling for $3,000. He died in 1944 at 46.

It comes from his sister Helena, who said his IQ was between 250 and 300. No test, examiner or date is given.

Even if a childhood test existed, scores that high came from the old ratio method and are not meaningful on a modern scale.

LifeScore lists 250 because it is the number people search for, and labels it as an unverified claim.

Sidis worked alone and followed his curiosity across mathematics, history and languages. He invented a language, collected streetcar transfers and wrote a long history of Native American tribes, using pseudonyms to keep his name out of print.

What supports it

• He enrolled at Harvard at age 11 in 1909 and graduated cum laude in 1914.
• In 1910 he lectured the Harvard Mathematical Club on four-dimensional bodies.
• He published The Animate and the Inanimate in 1925 and held a patent for a rotary perpetual calendar in 1930.

What it cannot prove

• The IQ claim names no test, date or examiner, and the family had a reputation for exaggeration.
• A 1933 civil service figure of 254 sometimes cited was probably a placement score, not an IQ.
• Ratio IQ at extreme values has no meaning on a modern scale.

William James Sidis's IQ is represented here by a retrospective estimate of 250, not a verified test result. William James Sidis is best known for exceptional early mastery. The useful question is what the surviving evidence shows, not whether a precise modern score can be recovered.

A famous child prodigy who withdrew from public life. Wrote widely under pseudonyms and avoided the attention that had followed him since childhood.

The dominant archetype here is The Outcast. This archetype shapes decision patterns: what feels natural, what creates friction, and what blind spots tend to emerge.

Estimated IQ is 250. This is a rough estimate based on documented accomplishments and contemporary accounts, not a literal measurement.

He patented a rotary perpetual calendar in 1930.