Before we get started let’s define what a ply is in chess:
A ply is a half move and a move is equivalent to 2 ply or a turn by each player. For example, 1. e4 is one ply and 1…e5 would be the 2nd ply, together these two plys make one move.
Getting close to the truth of a chess position requires the calculation of a minimum of 6 ply (3 moves). The higher your rating the higher the ply calculation requirement increases since your opponent will be delving more deeply into the position than you. If you calculate anything less than 3 ply you are playing hope chess, since you are not forseeing your opponent’s responses.
Below is an assessment of how calculation skill correlates to one’s chess rating:
0-1000 1 ply
1000-1200 2-3 ply
1200-1400 4 ply
1400-1600 6 ply
1600-1800 8 ply
1800-1900 10 ply
1900-2000 12 ply
Stopping your calculations too soon can prevent you from finding the winning move. Many times the winning move comes after a series of seemingly unfavorable moves, and stopping your calculation too soon will prevent you from finding the best move in the position. At the same time, not looking deeply enough into your opponent’s moves will cause you to miss defensive opportunities against your opponent’s threats.
Here’s a good example of a tactics puzzle where I did not find the correct answer because I stopped my calculations 1 ply too soon.
In this position I saw 1. Qxe5 and 1. Rd8+ as possible candidate moves. I then proceeded to analyze 1.Qxe5 Qxe5 2.Rd8+ which leads to the next position:
At this point I saw that the Black King seemed to be escaping via 2…Ke7 and he would also be attacking the undefended rook on d8. I stopped my calculations at this point and proceeded to analyze 1.Rd8 which also lead nowhere. If only I would have continued analyzing 1 ply deeper, I would have found 3.Re8# and White Wins. Here’s the winning position:
Consistently calculating at least 6 ply deep on most moves is one of the key improvements you can make in your thought process that will allow you to improve your chess skill.