Many people are interested in the question if there is a relationship between IQ and the chess rating (Elo) of a chess player. If there is a relationship between IQ and Elo, what sort of connection is it and what are the IQ ratings of famous chess players? How strong is the connection between chess ability and IQ? First let's take a look at what Grandmaster Jonathan Levitt writes in his book Genius in Chess (1997):

Back in 1988, there was an impressive chess festival in the small industrial town of Saint John, Canada. Two large and very strong Open tournaments were combined with the complete set of seven Candidates’ matches in the World Championship cycle of the time (Karpov was to join the seven winners). The English contingent were all on good terms and in good cheer (Nigel Short was making mincemeat of Sax in his match, likewise Jon Speelman of Seirawan) and usually formed, combined with certain selected 'foreigners' (like Spassky), a massive eating party which the local restaurants struggled to accommodate. I have a fair recall of the conversation on one such evening. Nigel Short was asked what he thought his IQ was. He was not sure, but (far too modestly) proposed 130 or 140. John Nunn, his second, suggested that with a little training, Nigel could knock his score up to at least 160. Speelman was not impressed by IQ tests generally, and everybody saw the inadequacy of any test which depended on how much practice you had had at the type of questions involved.

At this point, some bright spark (me) suggested that it might be a better measure of intelligence to do two tests and see how much the person improved. Quick as a flash, Nigel replied that this was a very bad idea since you could do deliberately badly in the first test! It took me a few seconds to grasp his meaning - that you could artificially inflate the difference in your scores and thus score better in the proposed test.

Everybody was fairly impressed by this quick and crafty answer and the conversation moved on. The story illustrates something important about the nature of the chess mind - how good it is at short cuts (no pun intended) and tricky ways round things. Mathematicians are usually less devious in their thinking - it is important to find direct ways to prove things.

[...] Before offering, very tentatively, my equation linking potential chess strength with IQ, I would like to say a little more about the IQ scale. Assuming, somewhat incorrectly as pointed out earlier (and it is true that from a false assumption you can deduce anything, but this sort of false assumption should be seen as just an inaccurate approximation), that intelligence follows the 'normal' distribution (mean 100, standard deviation 15), then how many really bright people would there be? The mathematical/statistical implications would be as follows:

16% above 115
2.3% above 130
0.13% above 145
0.003% above 160

This would correspond to there being approximately the following numbers of people above the given levels in England:

1,150,000 above 130
65,000 above 145
1500 above 160

This should give you a fair idea of the way the normal distribution works, though remember that these are underestimates of the actual numbers. It is very difficult to generalise about the type of characteristics people have at different levels of intelligence. The following attempt to do so, an excerpt from Choice Mathematics (book one) by Kevin of the Teachers, is certainly quite provocative: 'There appears to be a hierarchy of abilities and traits in those of high intelligence as follows, suggesting an order for teaching intelligence.'

IQ 185, High natural neuro-kinesthetic control; high curiosity drive; anti trivia; in a hurry
IQ 180, New creation
IQ 175, Knows intelligent (and right!)
IQ 165, Formalisation; beginnings of self confidence; less hiding
IQ 160, Interest in logic; paranoia; minor creation; recognises good work; art; music
IQ 150, Trivial formalisation
IQ 145, Below this level and often above is everywhere found a slavery to conditioning

If this is true, then I guess all us slaves to our conditioning had better hope that the conditioning is good conditioning! Now that the vast majority of readers are feeling suitably outraged, it is time to present the 'Levitt Equation'. I stress that this equation is subject to a number of reservations and should not be taken too seriously.

The Levitt Equation: Elo ~ (10 x IQ) + 1000.

You can read more (Characteristics of a chess genius and IQ and Chess strength) about it on the homepage of J. Levitt.

Some sources give Garry Kasparov, a renowned chess player, an IQ between 185 and 190. But in 1987-88, the German magazine Der Spiegel went to considerable effort and expense to find out Kasparov's IQ. Under the supervision of an international team of psychologists, Kasparov was given a large battery of tests designed to measure his memory, spatial ability, and abstract reasoning. They measured his IQ as 135 and his memory as one of the very best. I think this lower number is much more realistic than all those numbers above 140. Most IQ tests stop at about IQ 140 because you just can't design a good test for higher IQs. There are just not enough people to validate the test.

Especially when you read number like 185 (Bobby Fischer) or 220 (Leornado da Vinci) on the internet it becomes funny. But since people like fun here are some IQ numbers of famous people and chess players. Who measured those IQ numbers? I have no idea, but when something is written on the internet it is true!

Bobby Fischer Chess player USA 187
Donald Byrne Chess Player Irland 170
Garry Kasparov Chess player Russia 190
Judith Polgar Chess player Hungary 170
Robert Byrne Chess Player Irland 170

Abraham Lincoln President USA 128
Adolf Hitler Nazi leader Germany 141
Al Gore Politician USA 134
Albert Einstein Physicist USA 160
Andrew J. Wiles Mathematician England 170
Arnold Schwarzenegger Actor Austria 135
Baruch Spinoza Philosopher Holland 175
Benjamin Franklin Writer, scientist & politician USA 160
Benjamin Netanyahu Israeli Prime Minister Israel 180
Bill (William) J. Clinton President USA 137
Bill Gates CEO, Microsoft USA 160
Blaise Pascal Mathematician & religious philosopher France 195
Bonaparte Napoleon Emperor France 145
Buonarroti Michelangelo Artist, poet & architect Italy 180
Charles Darwin Naturalist England 165
Charles Dickens Writer England 180
Felix Mendelssohn Composer Germany 165
Friedrich Hegel Philosopher Germany 165
Galileo Galilei Physicist & astronomer & philosopher Italy 185
George W. Bush President USA 125
George Washington President USA 118
Gottfried Wilhelm von Leibniz Germany 205
Hillary Clinton Ex-President wife USA 140
Immanuel Kant Philosopher Germany 175
James Cook Explorer England 160
James Watt Physicist & technician Scotland 165
Johann Sebastian Bach Composer Germany 165
Johann Strauss Composer Germany 170
Johann Wolfgang von Goethe Germany 210
Johannes Kepler Mathematician, physicist & astronomer Germany 175
John Adams President USA 137
John F. Kennedy' Ex-President USA 117
John Locke Philosopher England 165
John Quincy Adams President USA 153
Joseph Louis Lagrange Mathematician & astronomer 185
Kim Ung-Yong Korea 200
Leonardo da Vinci Universal Genius Italy 220
Ludwig van Beethoven Composer Germany 165
Martin Luther Theorist Germany 170
Nicolaus Copernicus Astronomer Poland 160
Nicole Kidman Actor USA 132
Paul Allen Microsoft cofounder USA 160
Plato Philosopher Greece 170
Rembrandt van Rijn Artist Holland 155
René Descartes Mathematician & philosopher France 185
Richard Nixon Ex-President USA 143
Richard Wagner Composer Germany 170
Shakira Singer Colombia 140
Sharon Stone Actress USA 154
Sir Isaac Newton Scientist England 190
Stephen W. Hawking Physicist England 160
Thomas Jefferson President USA 138
Voltaire Writer France 190
Wolfgang Amadeus Mozart Composer Austria 165

And the winner is... Leonardo da Vinci. Have a nice day!