Why Does “K” Mean Strikeout in Baseball?

Written by Mark Bailey
Last updated on

A strikeout occurs when a batter accumulates three strikes without putting the ball into play. The strikes can be swinging or looking. A foul tip counts as a strike but cannot be the final strike in the at-bat (unless it’s a bunt attempt). A foul tip caught by the catcher is also considered a third strike. So why are these strikeouts represented in the scorebook with a K? 

In this blog post, we’ll explore the history of the strikeout and why it was given that specific letter designation. Stay tuned to learn more about this unique aspect of baseball!

History behind the letter K for strikeouts

Henry Chadwick was a journalist in the 1850s who covered baseball. He is widely regarded as one of the first to record the box score of a game. He came up with much of the shorthand still used in baseball scorekeeping today. Because of this, he is the only journalist officially enshrined in the Baseball Hall of Fame. Chadwick had already chosen “S” to stand for sacrifice in his scorebook, so he decided to use “K,” the last letter of “struck,” which was the most common way to refer to a batter in those days, who was out after three strikes.

K has become one of the most widely known terms of statistical shorthand. Fans will chant “K” when a runner has two strikes, and fans in stadiums hang posters of the letter K to indicate how many strikeouts a pitcher has accumulated.

What does a backwards K mean?

A backward K is used to indicate that no attempt was made to swing at the final strike of the at-bat. This is also known as a “called” third strike. Some pitchers can “freeze” a batter with a pitch that moves significantly and accumulate more backward Ks than most.

A traditional forward K indicates a swing and miss strikeout or a foul tip-out strikeout.

What is the K rate?

K rate, also known as strikeout rate and represented as “K%,” is used to measure the frequency with which a pitcher strikes out hitters. It is calculated by dividing total strikeouts by the number of batters faced and expressed as a percentage.

This metric is called SO% for hitters and is calculated by the number of times a batter strikes out divided by their total plate appearances.

Fun facts

Who has the most K’s in history?

Nolan Ryan is the all-time strikeout leader with 5,714 career strikeouts. Only 19 players have ever eclipsed 3,000 strikeouts, and the only active players on this list are Max Scherzer and Justin Verlander.

Other fun facts

  • Reggie Jackson holds the record for most strikeouts as a hitter with 2,597.
  • Roger Clemens (2), Kerry Wood, and Max Scherzer are the only pitchers to strike out 20 batters in a 9-inning game.
  • Tony Gwynn was notoriously difficult to strike out and finished his career with more doubles (543) than strikeouts (434).
  • The record for most consecutive batters struck out in a game is 10, most recently tied by Corbin Burnes of the Milwaukee Brewers.
  • Strikeouts can also be known as punchouts.

K’s are a pitchers best friend

If you are a pitcher, Ks can be your best friend. They can get you out of a jam, help you pitch efficiently, and generally terrify your opponents. Strikeouts are the surest sign that a pitcher is on their A-game. If you’re a batter, it just means a long, lonely walk back to the bench.

Featured image by David via CC BY 2.0