At the end of the second round of the Masters, a cut is made to reduce the field for the final two rounds. The Masters cut rule is determined is a little bit different than the three other majors and from week-to-week on the PGA Tour.
The Masters cut line is that the top 50 players and ties make the cut, as well any player within 10 shots of the lead (also referred to as the 10-Shot Rule).
The rule was changed in 2014, bumping up from the former cut line of the top 44 players and ties, which was the case from 1961-2013. Prior to that, the cut rule was the top 40 and ties.
In most years, that means approximately 40 players are cut from the field for the weekend.