Baseball Bat Drop: What Does It Mean?

“Bat drop” is a common phrase or expression used while talking about the size of a baseball or softball bat. It is a quick way to reference a bat’s weight relative to its length.

Bat drop is measured by subtracting bat weight in ounces from the bat length in inches.

Bat Drop = Length (in) – Weight (oz)

It is important to be aware of bat drops when shopping for a new bat. Not only will it be a guide to finding the appropriate size bat, most leagues and age groups determine the required bat drop players must use. For example, high school players are required to use drop 3 bats.

How to Measure Bat Drop

As mentioned above, bat drop is measured as a length to weight ratio. For example, a bat with a 33-inch length and a 30 oz weight, has a bat drop of -3. If that same bat has a weight of 31 oz, it will be a -2 bat drop. It is important to note that while two bats may both have the same bat drop, that doesn’t mean they are the same length or weight.

Almost all youth bats will have the length, weights, and bat drop clearly indicated. This is important to know so it can be determined if the bat is compliant for the applicable league. It is also possible to find the bat drop of a bat by simply weighing the bat and measuring the length. Sometimes wood bats are not clearly indicated, but it is easy to quickly figure out the bat drop with a scale and measuring tape.

When choosing an appropriate bat for a player, the league requirements should be the starting point. For instance, if the age group or league requires a -5 bat drop, that quickly narrows down the options. Now a player can focus on the length and in turn, a weight that feels good within those parameters. For instance, one player may prefer a 32in/27oz bat, while another may prefer a 30in/25oz bat, which in this case, is perfectly fine since both bats are compliant and meet the -5 requirement.

Bat Drop by Age & Level

Once again, always confirm with the league or age group when determining the appropriate bat drop requirement. Baseball and softball bats can have difficult return policies to work with, so it’s important to know a bat will be allowed in the league before starting to use it. It can turn into a pain if this is found out too late. Common governing bodies include USSSA & BBCOR. Below is a chart of common bat sizes by player’s size and age. Combined with the rules of a player’s league, this is a good starting point for choosing the right bat size.

Bigger27/15 (-12)28/16 (-12)29/17 (-12)29/19 (-10)30/20 (-10)31/21 (-10)31/23 (-8)31/26 (-5)33/30 (-3)
Average26/14 (-12)27/15 (-12)28/16 (-12)28/18 (-10)29/19 (-10)30/20 (-10)30/22 (-8)30/25 (-5)32/29 (-3)
Smaller25/13 (-12)26/14 (-12)27/16 (-12)27/17 (-10)28/18 (-10)29/19 (-10)29/21 (-8)29/24 (-5)31/28 (-3)
Player Age (Years) x Player Size

Other Considerations: Barrel Size, MOI, and Handle

Barrel Size

The common baseball bat barrel sizes are 2 3/4″ and 2 5/8″. Much like bat drop, the appropriate barrel size will be determined by the league or level that a player is at. Baseball bat manufacturers usually only produce bats that are in line with the most popular youth league regulations and other governing organizations. For example, at the high school level where -3 bats with 3 5/8″ barrel sizes are required, major manufacturers such as Louisville Slugger, Demarini, and Easton, will only produce -3 bats with this barrel size.


MOI stands for moment-of-inertia. In simple terms, this is how easy or difficult it feels to swing a particular bat. The weight distribution between different bats can drastically vary when comparing different models across different brands. Two bats may have the exact same length and weight, but one might feel significantly heavier while swinging. This is due to the weight distribution across the bat. A bat with more weight toward the handle will feel lighter to swing, and a bat will more weight toward the end of the bat will feel heavier.

Baseball manufacturers purposely have multiple models with different weight distributions because it comes down to personal preference. Some players prefer “end-loaded” bats while others may prefer a more balanced feel. As a player choosing a bat, it is important to be aware that different models will feel different from one another. If possible, it is always best to swing different models to determine which one feels best.


The handle on a bat can play a big part in the overall feel of a bat. The thickness and profile of the handle, along with the knob shape, can change the way a bat feels when swinging, making it feel lighter or heavier. Similar to weight distribution, the handle on a bat comes down to personal preference.

The purpose of pointing out these additional factors is to illustrate that there are many variables other than just the weight and length of a bat. Over time, players will usually hone in on their preferences naturally, but it may take some trial and error to find which bat works best. There is no perfect formula for determining the right bat size, and there is no right or wrong. A player should feel confident with their bat, and as long as it meets the regulations, that’s all that matters.