What is Slugging Precentage (SLG) in baseball?

The 2025 MLB season is quickly approaching and with that in mind, this is the perfect time to define some of the more complex statistics widely used in the sport.

One of these statistics is Slugging Percentage (SLG), which is the measurement of a player’s power by calculating their total bases per total at-bat.

Our article will explain how Slugging Percentage is calculated, explain the origins of Slugging Percentage, and give you the career and single-season leaders for Slugging Percentage.

How is Slugging Percentage calculated?

Unlike some of the other advanced statistics in baseball, Slugging Percentage has a defined formula. Per Baseball-Reference, this formula is the following:

Total Bases / Total At-Bats

While this is not a complex formula, it is important to mention that each type of hit is weighted differently. A single is worth one base, a double is worth two bases, a triple is worth three bases, and a homerun is worth four bases.

That in turn, makes the following formula a more accurate representation of what you are calculating:

(Singles + (2 x Doubles) + (3 x Triples) + (4 x Homeruns)) / Total At-Bats

Keep in mind that Slugging Percentage does not take walks or hit-by-pitches into account. It solely calculates the amount of power of a player per each at-bat throughout their season or career.

Origins of Slugging Percentage

Before Slugging Percentage became an official statistic, a baseball player's success was measured solely by their batting average and the number of home runs they hit.

However, only looking at a player’s home run ability did not provide the full picture.

Because of this, Branch Rickey coined the term “Extra Base Power” (EBP) in 1954 to help establish a way to look at more than just home runs and batting averages. EBP ended up being the predecessor to Slugging Percentage and the formula we have today to calculate a player’s power.

Highest Single-Season and Career Slugging Percentage

Below we have listed the top five Slugging Percentage leaders for a career, single-season, and the top current active leaders per Baseball-Reference.

MLB Career Slugging Percentage (SLG) Leaders

Player	SLG
Babe Ruth	.689 (1914-1935)
Ted Williams	.633 (1939-1960)
Lou Gehrig	.632 (1923-1939)
Mule Suttles	.619 (1921-1944)
Turkey Stearnes	.615 (1923-1945)

MLB Single-Season Slugging Percentage (SLG) Leaders

Player	SLG
Josh Gibson	.974 (1937)
Mule Suttles	.877 (1926)
Charlie Smith	.869 (1929)
Josh Gibson	.867 (1943)
Barry Bonds	.863 (2001)

MLB Active Slugging Percentage (SLG) Leaders

Player	SLG
Aaron Judge	.604 (2016-Present)
Mike Trout	.580 (2011-Present)
Shohei Ohtani	.574 (2018-Present)
Juan Soto	.532 (2018-Present)
Giancarlo Stanton	.525 (2012-Present)

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