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How Big is a Baseball – MLB Baseball Size and More

Here’s the skinny: Folks around the diamond often toss around “9 inch balls” like it’s a secret handshake. But, as with all things in the beautiful game, there’s a saga woven into that little sphere of leather that’s worth tipping your cap to. Let’s dive into the dimensions of baseballs used at various levels, shall we?

For those seeking the dimensions of a baseball field, I recommend reading my comprehensive article, “Complete Guide to Baseball Field Layout.”

How Big is a Baseball - Size of a Baseball Comparison
9 in baseballs vs Various softball sizes
(photo by author)

Table of Contents

History of Baseball Sizes and Weights

Despite advancements in manufacturing that lead to more uniform baseballs, the process still requires human hands, leading to minor size differences between balls.

According to MLB Rule 3.01 (2021), an official league baseball must have a circumference between 9 and 9.25 inches (22.86 to 23.495 cm) and weigh around 5 ounces (141.75 grams). Its core is a blend of cork and rubber, wrapped in wool and cotton yarn layers, encased in cowhide, and stitched together with red thread.

These specifications set by Major League Baseball are also adopted by youth, high school, and college leagues. However, balls designed for very young players may be made smaller to accommodate their needs.

Why is the Standard Size of a Baseball Important?

In the early days of baseball, there was significant variability in the size, weight, and materials of baseballs due to regional differences and the handmade nature of the equipment. This lack of standardization led to balls that were often “livelier” and could significantly affect gameplay, including scoring.

According to the Smithsonian Magazine, it wasn’t until the mid-1850s that efforts to standardize the baseball began, aiming for a more uniform weight and size. However, it took several decades for these standards to fully evolve, impacting strategies, home-field advantages, and the very nature of early baseball games.

How Big is a Baseball - Pitchers Extra Large Hand
Donye Evans’ Extra Large Hand
Normal Adult

Of course, the standard baseball size can be advantageous with those pitchers with massive hands like Donye Evans (he is 6′ 6″ tall and with a baseball in his palm, he can touch all his fingers without touching the ball!).

Baseball Size Specifications

In this section, we dive into the core measurements that define a baseball, peeling back the layers on its size. Our exploration zeroes in on three critical dimensions: the circumference, diameter, and radius.

The Circumference of a baseball

Rawlings, which produces all MLB and MiLB baseballs, follows the guidelines set by the MLB for baseball circumference.

The current standard circumference of an MLB baseball is between 9 and 9.25 inches (23 cm and 23.495 cm), measured at its widest point around the equator of the ball.

Circumference of an MiLB baseball

What is the Diameter of a Baseball

The diameter is the distance across the sphere passing through the center (called the “great circle”).

In the case of an MLB baseball, this can be determined by dividing the circumference by the constant Pi (approximately 3.14159).

Diameter of an MiLB baseball
Pi (π)
Pi is the ratio of a circle’s circumference to its diameter. It’s a constant in mathematics and approximately equals 3.14159. We use Pi in calculating both the surface area and volume of a sphere.

To calculate the diameter, we use the following formula:

  • diameter = circumference / pi
  • diameter (smaller circumference) = 9 / 3.14159; or
  • diameter (larger circumference) = 9.25 / 3.14159

So, an average diameter of an MLB baseball is 2.86 to 2.94 inches or in metrics, 7.28 to 7.48 centimeters.

Radius of a Baseball

The radius of a sphere is simply half the distance of its diameter.

  • radius = diameter / 2
  • radius (smaller circumference) = 2.86 / 2; or
  • radius (larger circumference) = 2.94 / 2

So, an MLB baseball has an average radius of about 1.43 to 1.47 inches (3.64 to 3.74 centimeters).


We need to keep in mind that the relationship between size and weight isn’t straightforward; it’s influenced by an object’s volume and density. Two items of the same size can have different weights if they’re made from materials with different densities.

Size vs. Density

For instance, a cork and a steel ball of the same volume will weigh differently due to steel’s higher density. Similarly, a large, air-filled balloon doesn’t weigh much more than a small, uninflated one, showcasing how air’s low density affects weight. Understanding these distinctions helps clarify misconceptions about how size and weight correlate.

Baseball Ball Sizes – Sphere, Surface Area, and Volume

Now that we have the radius and we understand Pi, let’s move on to calculating the surface area and volume of an MLB baseball.

Is Baseball a Perfect Sphere?

As anyone who has ever picked up a baseball knows, it’s a excellent example of a geometric figure known as a sphere. Spheres are round, three-dimensional objects in which all points on the surface are an equal distance from the center.

However, a baseball ball is not a perfect sphere because the winding may not be perfectly even, which can lead to slight variations in the thickness of the baseball in different places. Additionally, the layers of yarn are covered by two leather pieces stitched together with red thread, forming the outer shell of the baseball. The stitches themselves, known as the seams, can cause the baseball to deviate from being a perfect sphere as they protrude from the surface.

Surface Area

The surface area is an area that a pitcher’s fingers contact while throwing the baseball.

The formula for calculating the surface area of a sphere is:

Baseball Sphere
  • surface area = 4πr²

This formula tells us that the surface area is four times Pi times the radius squared.

  • surface area = 4 (3.14159) (1.45) (1.45)
  • surface area = 26.42 sq. inches (170.46 sq. cm)

Substituting our average radius of 1.45 inches (3.683 cm), we find that an MLB baseball has a surface area of about 26.42 square inches (170.46 square centimeters).


The formula for calculating the volume of a sphere is:

  • Volume = (4/3) π r³
  • Volume = (4/3) (3.14159) (1.45) (1.45) (1.45)

This formula tells us that the volume is four-thirds of Pi times the radius cubed.

Using our average radius, an MLB baseball has a volume of about 12.77 cubic inches or 209.26 cubic centimeters. This gives us an understanding of how much space the baseball occupies.

Comparing Ball Sizes

You might be wondering how manufacturers produce different types of baseballs if the size of a baseball is the same across the board.

Size of a Baseball Compared to Other balls

When manufacturing baseballs, controlling the volume and surface area while varying the mass essentially involves changing the internal composition of the baseball. This can be achieved by varying the density of the materials used, the amount of winding (how tightly the yarn or string is wound), or the materials themselves.

Varying Density

The core or the winding materials could have different densities. A high-density material will increase the mass of the baseball without changing its volume. For example, using a rubber core instead of a cork core could increase the density and hence the mass of the baseball, because rubber is denser than cork.

Varying Winding Tightness

The tightness of the windings around the core can also impact the mass. Tighter windings could lead to a higher mass, as more material (yarn, string) is packed into the same volume.

Varying Materials

The materials used in the windings or the core could be varied. Different materials have different masses, even if their volume is the same (due to differences in density). For example, a baseball with a cork and rubber core and wool windings will have a different mass from a baseball with a pure rubber core and cotton windings.

All of these changes could potentially affect how the baseball performs.

It’s important to note that the rules of professional baseball specify the mass, circumference, and materials of a baseball, so there’s less variability in that context. However, for practice, novelty, or recreational purposes, baseballs can have a variety of masses, sizes, and compositions.

Which Baseball will Travel Farther? A heavier baseball or a lighter baseball?
The distance a baseball travels when hit is influenced by its weight due to Newton’s Second Law of Motion. Lighter balls accelerate faster when hit but are more affected by air resistance. Conversely, heavier balls, while requiring more force to move, resist air resistance better.

However, the actual distance depends on other factors like pitch speed, bat speed, ball spin, and atmospheric conditions. In professional games, baseballs are made to specific weight standards for fairness. For more information on the topic of baseball weight, please read my post, How Much Does a Baseball Weigh – Official Baseball Ball Weight

Baseball Sizes by Age

It is important to recognize that not all baseballs are created equal. Depending on a player’s age and skill level, different sizes of baseballs are used to ensure player safety and foster age appropriate development.

In this section, we’ll delve into the specifics of how baseball sizes vary by age, laying out a comprehensive guide to help you understand and select the right baseball for each stage of a player’s journey.

T-Ball (Ages 3-5)

For the youngest players, a softer and smaller training balls are often used to accommodate their small hands and undeveloped motor skills .

These balls are typically made of softer materials like foam or softer composites to reduce the risk of injury. They have a circumference of around 8.5 to 8.75 inches and weigh around 4.5 ounces.

Youth Baseball (Ages 6-10)

As players grow and develop their skills, they transition to a harder but still slightly smaller than regulation baseball.

These balls generally have a circumference of 8.75 to 9 inches and weigh between 4.75 and 5 ounces.

Intermediate/Youth Leagues (Ages 11-12)

Players in this age range use baseballs closer to the regulation size used in high school and professional leagues. These balls have a circumference of 9 to 9.25 inches and weigh around 5 ounces.

Most baseballs used at this level have reduced performance characteristics (such as larger cork core or less bouncy pill) to minimize the injury risk.

Older Youth Leagues (13-14)

Players in this age group use regulation-size baseballs. According to Major League Baseball standards, these balls have a circumference of 9 to 9.25 inches and weigh between 5 and 5.25 ounces.

Some leagues will continue to utilize baseballs with safety features for their rec leagues. At the tournament level of competition, “regular” baseballs are used.

High School/College/Professional (Ages 14 and Up)

At these levels, players use regulation-size baseballs. According to Major League Baseball standards, these balls have a circumference of 9 to 9.25 inches and weigh between 5 and 5.25 ounces.

This progression of baseball sizes by age allows players to gradually adjust to the weight and feel of a regulation baseball, preparing them for higher levels of play. It’s important to note that standards may vary slightly depending on the specific league or country. Always check with your league to ensure you’re using the correct ball size.

If you want to see a detailed list of recommended baseballs for each age group, please read the Different Types of Baseballs for Different Ages post.

Fun Brain Exercise – Guess How Many Baseballs Can You Fit Inside

Do you want more math? Dive into this playful mental workout and engage your brain, consider the ball’s dimensions, and let your imagination run wild with guesses. It’s a fun way to visualize spatial relationships and sharpen your estimation skills, all wrapped up in the love for the game.

Regular 5 gallon bucket

A single U.S. gallon holds 231 cubic inches, so a 5-gallon bucket encompasses 1155 cubic inches. To translate this volume into more manageable units, we convert cubic inches to cubic feet by dividing by 1728 (the number of cubic inches in a cubic foot), yielding roughly 0.668 cubic feet. For conversions to liters, we divide by 61.024, resulting in approximately 18.93 liters.

5 gallon buckets

Calculating a baseball’s volume involves the formula for the volume of a sphere, (4/3)πr3, with Major League Baseballs having a diameter between 2.86 and 2.94 inches, thus an average radius of 1.45 inches gives us a ball volume of 12.7 cubic inches.

Considering the geometric packing efficiency of spheres, which is roughly 74%, the usable volume of the bucket for holding baseballs is 854.7 cubic inches. Dividing this by the volume of a single baseball tells us that around 67 baseballs can fit into a 5-gallon bucket. This theoretical number does not account for the practical challenge of the top layer of baseballs possibly causing an overflow if the bucket is filled to the brim.

Extra tall, 6 gallon bucket

One U.S. gallon holds 231 cubic inches, making the volume of a 6-gallon bucket 1386 cubic inches. To express this in different units, 1386 cubic inches equals about 0.802 cubic feet or 22.71 liters, establishing the capacity of a standard 6-gallon bucket.

6 gallon bucket

With the volume of a Major League Baseball around 12.7 cubic inches, and considering a packing efficiency of roughly 74% due to space between the spheres, the effective volume within a 6-gallon bucket for baseballs calculates to 1025.64 cubic inches.

Dividing this effective volume by the volume of one baseball, we find that approximately 80.76 baseballs could theoretically fit into the bucket. However, due to practical considerations, such as the impossibility of fractioning a baseball and the irregularities from stitching, a more realistic estimate is closer to five dozen, or 60 baseballs, to comfortably fit within a 6-gallon bucket with the lid secured.

2020 Dodge Grand Caravan

Edmunds highlights the Dodge Grand Caravan’s roominess, noting dimensions including a 67.9-inch height, a 202.8-inch length, a 121.2-inch wheelbase, and a 78.7-inch width. These dimensions afford the Caravan 33 cubic feet of cargo space with the third row down and a whopping 143.8 cubic feet with the second-row seats folded.

2020 Dodge Grand Caravan Storage Space

To visualize how many Major League Baseballs could fit into such a spacious vehicle, consider the volume of a baseball at approximately 12.7 cubic inches. Converting this to cubic feet for compatibility with the vehicle’s cargo space measurements, we find that a baseball occupies roughly 0.00736 cubic feet.

Given the packing efficiency for spheres is about 74% due to the unavoidable gaps between them, the usable cargo space for baseballs in the 33 cubic feet area is about 24.42 cubic feet. Dividing this by the volume of a single baseball suggests that around 3320 baseballs could theoretically fit into this space when the seats are stowed.

Full-sized School Bus

In the U.S., the dimensions of a standard full-sized school bus span roughly 35-45 feet in length, 8 feet in width, and about 6.5 feet in height internally, resulting in an interior volume between 1820 and 2340 cubic feet. Factoring in the space occupied by seating, the driver’s compartment, and aisles—which could take up about half of this volume—the usable space for storage might drop to approximately 910-1170 cubic feet.

Full-sized school bus

Averaging this adjusted volume to around 1040 cubic feet and using the previously mentioned baseball volume of roughly 0.00736 cubic feet, we encounter the packing efficiency dilemma; only about 74% of the bus’s volume can effectively be used due to the inherent gaps when packing spherical objects like baseballs. This reduces our usable space to 769.6 cubic feet.

By dividing this adjusted volume by the volume of a single baseball, we find that a typical full-sized school bus could theoretically accommodate about 104,500 Major League Baseballs. This number, while impressive, is a theoretical estimate that simplifies many real-world complexities, such as the non-uniform shape and stitching of baseballs and the intricacies of maximizing space utilization.

Ferrari F40

Car and Driver magazine notes that the Ferrari F40 features a modestly sized front storage area, commonly known as a “frunk” in vehicles with mid or rear engines, with an estimated capacity of about 4.7 cubic feet. Given that the shape of this compartment and the types of items being stored can greatly influence its practical utility, the real-world effectiveness of this space for storage purposes might be less than its raw volume suggests.

Ferrari F40 Storage Compartment

Considering the volume of a Major League Baseball is roughly 0.00736 cubic feet, and applying the 74% efficiency typically achievable when packing spherical objects due to the spaces between them, we find that the Ferrari F40’s frunk could theoretically accommodate: 0.74×4.7 cubic feet=3.478 cubic feet

Dividing this adjusted volume by the volume of a baseball provides an estimate of how many baseballs could fit: 3.478 cubic feet÷0.00736 cubic feet/baseball≈472 baseballs

Thus, in theory, the Ferrari F40’s storage space could hold approximately 472 Major League Baseballs. This calculation, while intriguing, simplifies various practical considerations like the compartment’s shape and the items’ adaptability to such a confined space.

Minute Maid Park Stadium (Houston Astros)

Minute Maid Park, the Houston Astros’ stadium, adjusts its seating capacity based on the time of day, accommodating approximately 41,168 spectators for night games and 42,060 for day games. The park’s layout extends 332 feet to the left-field line, 435 feet to center field, and 326 feet to the right-field line.

Minute Maid Park

Assuming the shape of the stadium roughly forms a half-cylinder—a simplistic model—the radius can be determined by averaging the field dimensions, and an estimated height can represent the structure of the stands and roof.

By calculating with a radius of approximately 364.33 feet (the average of the field’s dimensions) and an assumed height of 100 feet, alongside the length of the field’s longest dimension (435 feet), we can estimate the volume of Minute Maid Park. Using the formula for a half-cylinder’s volume, the stadium’s approximate volume comes out to around 20,903,500 cubic feet.

Given the volume of a Major League Baseball is about 0.00736 cubic feet, and accounting for the 74% packing efficiency due to gaps between packed spheres, approximately 2.1 billion baseballs could theoretically fit into Minute Maid Park! This estimation, however, simplifies many real-world complexities, including the stadium’s actual dimensions and features, not to mention the retractable roof that affects the calculation for a fully enclosed space as well as space taken up by various seats.


We dove into a world where physics meets sport, where the sphere’s size, surface area, and volume play critical roles in determining the outcome of each pitch and hit.

Whether you’re a player trying to master the curveball or a fan watching from the stands, appreciating the size of a baseball adds another layer to the enjoyment of this timeless sport.

So next time you watch a game or hold a baseball and ask “How big is a baseball?”, remember that it’s not just about how big the baseball is, but also about how this size shapes the very essence of the game.

Please don’t forget to visit Resource page containing chockful of all baseball ball related posts!

Frequently Asked Questions

Our FAQ section contains many of your burning questions about baseball sizes.

What is Inside a Modern Baseball

What is the Weight of a Baseball

What is the diameter of a baseball?

  • The diameter of a baseball is approximately 2.9 inches.

What is the circumference of a baseball?

  • The circumference of a baseball is between 9 and 9.25 inches.

What is the volume of a baseball?

  • The volume of a baseball is about 13.41 cubic inches.

What is the surface area of a baseball?

  • The surface area of a baseball is approximately 28.27 square inches.

How does the size of a baseball affect how far it can be thrown or hit?

  • The size of a baseball affects its air resistance or drag. A larger baseball would be harder to throw fast and wouldn’t travel as far when hit because of greater air resistance. Conversely, a smaller baseball would have less air resistance and could be thrown faster and hit further.

Why is the size of a baseball standardized?

  • The size of a baseball is standardized to ensure fairness in gameplay. It allows all players to compete on equal terms and makes it possible to compare performances across different games and leagues.

What material is used to make a baseball, and how does it contribute to its size?

  • A baseball is made from a core of cork or rubber, which is then wrapped in yarn and covered in cowhide leather. The materials and the tightness of the wrapping determine the baseball’s size and weight.

How does the size of a baseball affect pitching?

  • The size of a baseball affects the grip, which influences the types of pitches that can be thrown. The surface area (affected by the size and the stitching) also plays a role in the ball’s aerodynamics, affecting how it moves through the air.

How does the size of a baseball compare to other balls used in sports?

  • A baseball is smaller than a basketball, soccer ball, or volleyball but larger than a golf ball or a tennis ball. Its size is similar to that of a cricket ball.

Have there been changes to the standard size of a baseball over the years?

  • The size and weight of a baseball have been standardized since the late 19th century. Minor changes have occurred, often in response to changes in the game or advances in materials and manufacturing techniques, but the size has remained largely consistent.