The area where baseball pitchers warm up is called the bullpen.

In Major League and minor league stadiums, the bullpens are typically located in foul territory between each team’s dugout and the corresponding outfield wall, down the first- or third-base line.

Who Uses the Bullpen?

Generally, bullpens are used by relief pitchers during games in preparation for coming into the game in place of a starter.

Depending on the pitchers, the weather, and the situation, a manager or pitching coach will send one or two pitchers to the ‘pen to start warming up several minutes before the substitution is made.

Starters sometimes also warm up in the bullpen, generally between innings to keep their arms limber and fluid, but occasionally before games, too. Often, though, starters warm up on the game mound.

In any case, especially in the modern game, the emphasis in the use of the bullpen is warming up just enough without adding too much to a pitcher’s overall pitch count.

How Big Are Bullpens?

Though bullpens may vary in location, size, and configuration, one commonality is that nearly all of them feature a mound positioned sixty feet and six inches from the “plate,” where the practice catcher (bullpen catcher) or pitching coach catches warmup pitches.

(Every once in awhile you might find a backup catcher from the active roster, or a former catcher with name appeal, helping out in the bullpen.)

That distance — sixty feet, six inches — matches the regulation distance from the mound to home plate in the major and minor leagues.

What Is the Origin of ‘Bullpen’?

The origin of the term “bullpen” has long been a topic of debate within the game.

An early explanation drew on how baseball teams handled overflow crowds, when more patrons flooded into a stadium than there were seats to accommodate them.

In those cases, many teams would “herd” the excess fans into fenced off sections near the outfield walls, where they could stand and watch the game.

Because fans were herded like cattle, the story goes, the areas where they were “penned” in became the bullpens.

And, because of space considerations, relief pitchers often ended up doing their warmups right in front of the bullpens.

Other theories that have gained at least some support over the years include …

  • The proximity of warmup areas to Bull Durham display ads on outfield walls
  • The similarity of relief pitchers being sent in to face hungry batters to bulls being sent to their slaughter, both after being held in “pens”
  • Casey Stengel lamenting that his relief pitchers liked to sit around and shoot the bull(crap)
  • The parallels between bulls in a rodeo being penned up before being unleashed into the arena and relief pitchers similarly bottled and released
  • Announcer Jon Miller’s assertion that there was an actual pen with actual bulls near the outfield in the Polo Grounds (home of the New York Giants), close to where pitchers warmed up

The truth may be an amalgamation of multiples of these ideas, and maybe others, but the salient point is that the term “bullpen” is a vital part of the baseball lexicon.

It’s also worth noting that “bullpen” has become synonymous with the actual relief corps of a team over the years.

So, a baseball club in the 21st century might have five or six starting pitchers and a bullpen consisting of another 8-10 relief pitchers.

And … all of them warm up in the bullpen, at one time or another.