Pawn to Queen probabilities chart

Question

Statistically speaking, which white and black pawns are most likely to be queened?

Answer 1

I have some partial statistics for the question, from the Million Base 1.74 database, a collection of 1742057 games. 77218 of these games (4.4%) feature at least one promotion.

I counted 49970 promotions for white (54% of all promotions) and 42519 for black (46%). Here are the destination square statistics (meaning there is no track of the actual initial pawn square, because that statistic is a lot more difficult to gather), for all games and depending on the type of castling:

White         a8    b8    c8    d8    e8    f8    g8    h8
all         15.8% 14.2% 13.8% 14.8% 11.5% 11.3%  8.7%  9.8%
with O-O    15.8% 14.3% 13.9% 15.9% 11.8% 11.2%  8.1%  9.1%
with O-O-O  17.1% 14.7% 14.2% 10.7%  9.9% 11.7% 10.8% 11.0%

Black         a1    b1    c1    d1    e1    f1    g1    h1
all         16.0% 14.7% 14.4% 12.6% 11.8% 11.3%  9.0% 10.1%
with O-O    15.9% 14.8% 14.3% 12.9% 11.9% 11.3%  8.7% 10.0%
with O-O-O  13.5% 10.7% 10.9%  9.7% 12.4% 14.0% 14.0% 14.8%

A few observations:

• queenside promotions seem significantly more common than kingside promotions
• column statistics are quite consistent between black and white (except maybe when black castles long)
• castling long increases the odds of a promotion happening kingside

Answer 2

This is almost impossible to answer, but I would say the pawns that are on the a and h file or more likely to promote, especially if protected by another pawn and rook. I would say this increases if the king has already castled on the opposite side of the a or h file.