A 4-iron is a type of golf club. It has the most loft of the so-called "long irons" (irons 1-4). A player with a 90-mph swing can expect to hit a 4-iron for about 163 yards, with a fairly low arc.

With the virtual extinction of the legendary 1-iron, and more and more players replacing even the 2-iron and the 3-iron with hybrid clubs, the 4-iron is the longest iron many golfers still play nowadays, and some players are even starting to replace the 4-iron with a 4-hybrid. When the 4-iron is played, it sees the most use on windy days, when its low arc can help keep the ball below the wind.