Opening Frequency

 I did a little survey of chess opening frequencies from several chess databases. After looking over a million games or so and keeping tabs of the first few moves, these are the results.

1.e4 was the most common opening, representing 70% of the sample. This was followed by 1.d4, representing 20%. This frequency of 1.d4 goes up as more master games are included and amateur games excluded.  More amateurs still prefer 1.e4 over 1.d4.  More grandmasters prefer 1.d4 over 1.e4.

The next most common was 1.c4 (the English opening), representing 5% of the sample. Again, this number goes up with more master games and less amateur games. But our sample represents chess at all levels.

The next most common was 1.Nf3 (the Reti or King's Indian Attack), representing 4% of the sample. Thus, 1.e4, 1.d4, 1.c4, and 1.Nf3 represent 99% of all openings in most databases.

The next most common was 1.b3 (Larsen's Opening), closely followed by 1.b4 (Polish or Orangutan), 1.f4 (Bird's Opening) and 1.g3. These openings represented .9% of the sample.

Next came 1.Nc3 (Dunst), 1.g4 (Grob), 1.e3, 1.Na3, and 1.Nh3

The rarest moves were 1.a3, 1.c3, 1.f3, 1.h4, 1.d3, 1.a4, and finally 1.h3.

The most common response to 1.e4 was 1...e5. The next most common was 1...c5 (the Sicilian Defense).

Next came 1...e6 (the French Defense), followed by 1...c6 (Caro Kann).

Next in frequency was 1...Nf6 (Alekhine's Defense), 1...d5 (Center Counter), then 1...d6 (Pirc).

Next came 1...g6 (Pirc), 1...Nc6 (Nimzovich Defense), followed by 1...b6 (Owen's Defense).

Then came 1...a6, then 1...g5.

Finally, the rarest moves were 1...f6, 1...a5, 1...Nh6, 1...Na6, 1...f5, 1...h5, and 1...h6. I found no 1...b5 move.

The most common response to 1.d4 was 1...Nf6, followed closely with 1...d5.

Next came 1...f5 (Dutch). These 3 moves represent over 90% of the responses to 1.d4.

Next in frequency was 1...e6, followed by 1...c5.

Still rarer were 1...b6, 1...b5, 1...d6, 1...Nc6, 1...g6, and 1...e5

Finally, the rarest moves were 1...c6, 1...h6, 1...Nh6, and 1...f6.

I found no 1...a5, 1...a6, 1...Na6, 1...g5, or 1...h5.