What is the Strike Zone in Baseball?

The strike zone is the area over home plate where the pitcher is trying to throw the ball.

It’s an imaginary rectangle.  The width is determined by home plate (17″).  The height of the strike zone is from the batter’s “midpoint” (the midpoint between top of shoulders and belt) and the “hollow of the knees”… which means the back of the knees where they bend.

What is the Strike Zone in Baseball?

Definition of Strike Zone

Official MLB Rules Excerpt, here’s the official definition of a strike zone:

According to official MLB rules, the STRIKE ZONE is that area over home plate the upper limit of which is a horizontal line at the midpoint between the top of the shoulders and the top of the uniform pants, and the lower level is a line at the hollow beneath the kneecap. The Strike Zone shall be determined from the batter’s stance as the batter is prepared to swing at a pitched ball. (For diagram of STRIKE ZONE, see Appendix 5.)

Source:  Official MLB Rules PDF

What are the Baseball Strike Zone dimensions?

• Width of Baseball Strike Zone is always the width of home plate – 17 inches
• Height of Strike zone depends the hitter and the League (more info below)

Does the strike zone change based on height?

The answer is yes, the height of the strike zone changes based on the hitter.  This image provides a great example of what that looks like for tall baseball player vs a shorter one.

What is the Strike Zone in Little League Baseball?

No, the Little League strike zone is not the same as the MLB strike zone.  Here’s how Little League Baseball defines it:

The Little League Strike Zone (2.00) “The STRIKE ZONE is that space over home plate which is between the batter’s armpits and the top of the knees when the batter assumes a natural stance. The umpire shall determine the strike zone according to the batter’s usual stance when that batter swings at a pitch.”

Source for Little League Definition and Image

What is a strike? (official definition)

According to the official rules for MLB in 2021,  “A STRIKE is a legal pitch when so called by the umpire, which:

• (a) Is struck at by the batter and is missed;
• (b) Is not struck at, if any part of the ball passes through any part of the strike zone;
• (c) Is fouled by the batter when he has less than two strikes;
• (d) Is bunted foul;
• (e) Touches the batter as he strikes at it;
• (f) Touches the batter in flight in the strike zone; or (g) Becomes a foul tip.”

A History: Evolution of the Strike Zone in Baseball

Batters’ own strike zone

Believe it or not, back in 1876, baseball batters could determine their own strike zones.

They could tell the umpire if they wanted the pitch to be high, fair, or low. They notified the umpire and the pitch had to be thrown at the batters’ desired strike zone.

• The high strike zone was between the batter’s shoulders and waist
• The fair strike zone was between the batter’s shoulders and at least one foot from the ground
• The low strike zone was between the batter’s waist and at least one foot from the ground

1886 – 1887: The first official strike zone

Batters’ own choice of selecting their pitch led to conflicts between pitchers and umpires. Pitchers often complained about umpires making unfair decisions about the pitch. 

This led to the American Association defining such a zone for the first time. The rule stated that the pitch must be delivered at the height called for by the batter. If at such height it passed over any part of the plate and the batter failed to swing the bat, it was a strike.

According to the baseball encyclopedia Baseball Almanac, the first official strike zone was defined by the National League in 1887. The area was between the batter’s shoulders and knees. A pitch had to be passed below the batter’s shoulders and above the batter’s knees to be called strike. Batters could no longer define their own strike zones. They had to play according to this defined strike zone.

• 1950 – 1962: The newly defined strike zone
• In 1950, the strike zone was changed as an area between the batter’s armpits and the top of his knees during his batting stance.
• 1963 – 1968: The restored original strike zone
• In 1963, the originally defined strike zone of 1887 between the top of the batter’s shoulders and below his knees during his batting stance was restored.
• 1969 – 1987: The second-strike zone restored
• In 1969, the strike zone was once again changed as an area between the batter’s armpits and the top of his knees.
• 1988 – 1995: Upper and lower strike zone levels
• In 1988, a new area of the strike zone was defined which was a horizontal line. It began from the midpoint between the top of the shoulders to the top of the knees. The umpire had to determine the strike zone by the batter’s batting stance.

Current definition

In 1996, the baseball strike zone was redefined. The lower zone was expanded to the hollow beneath the kneecap. The upper part was defined from the midpoint between the top of the shoulders to the top of the uniform pants. The lower part was defined from the top of the knees to the hollow below the kneecap.

Strike Zone Judgment Statistics

Umpire has to define the official strike zone according to the batter’s stance as per official strike zone rules. It is an area that does not exist so the umpire has to make an estimate by himself. 

However, umpires are humans and human beings are prone to errors. 

Umpires make correct judgment for 99.5% of baseball games. However, there are many instances where errors occur in judging the strike zone. According to a 2018 study by Boston University, umpires made 34,294 wrong calls of strikes and balls. It is an average of 14 wrong calls per game.

In the same study, researchers have derived the percentage of umpire blind spots at the strike zone for that year:

• 26.78% for the top left of the strike zone
• 13.55% for top middle of the strike zone
• 26.99% for top right of the strike zone
• 14.34% for the bottom left of the strike zone
• 10.50% for bottom middle of the strike zone
• 18.25% for bottom right of the strike zone

Protective Equipment for Good Strike Zone Performance

Playing effectively in the strike zone and passing good judgment has much to do with being comfortable on the field. If you are not comfortable you cannot perform well. Your mind and body have to be involved in the game for a better performance.

For that, you need to equip yourself with safe and high-quality equipment. If players do not employ safe equipment, then they are prone to injuries. According to USA Today, last year, the injury rate of MLB players rose in 2019.

• A hamstring injury had an increase of 193%
• Soft tissue injury had an increase of 160%
• Oblique strains and tears had an increase of 83%

As of this writing, covers.com reports 274 players of Major League Baseball are on the injured list.

A 1996 study by Consumer Product Safety Commission (CPSC) estimates that protective baseball equipment reduces 36% of injuries to children each year.

The following protective equipment is important to affect the safety and performance of umpires and players on the field:

• Baseball Hats
• Baseball Helmet
• Baseball Gloves
• Baseball Wrist Guards

You can buy this equipment from your nearest sports shop or Click here to buy them online.