Easton Swing Weight Index Explained

If you’ve taken a look at the Easton BBCOR baseball bat lineup, whether it be past or present, then you may have noticed a unique feature. Easton uses what is called the Swing Weight Index (SWI), which is exclusive to their baseball bats, to help differentiate between their particular models and measure how hard it is to swing a particular design. JustBats understands that the Swing Weight Index from Easton might cause confusion, so we'll break it down and describe what it entails.

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The Swing Weight Index is established by the Moment of Inertia (MOI) and will depend greatly upon four different factors of an Easton BBCOR baseball bat:

• The Length
• The Material (composite or aluminum)
• The Barrel Size
• Whether there is a balanced or end loaded design

Watch this video created by our friend Henry who is the category manager for bats at Easton baseball. He explains in great detail exactly what the Swing Weight Index is and how it is defined.

The dictionary definition of moment of inertia (also known as angular mass or rotational inertia) is a quantity expressing an object’s tendency to resist angular acceleration. It is the sum of the products of the mass of each particle in the object with the square of its distance from the axis of rotation. It is also defined as the torque needed for a desired angular acceleration about a rotational axis. Wait, what? Confusing, right?

In simpler terms, MOI is the measure of resistance, while Easton’s SWI helps determine how heavy or light swinging a particular bat is. To tie it all together, a baseball bat with a low SWI, such as the new MAKO BEAST, is evenly balanced and delivers power through fast swing speeds. Meanwhile, a bat with a high SWI, such as the Z-CORE XL, is more end loaded and produces power with more mass behind the ball at impact.

*This is the 2016 chart, but it is still accurate.

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