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Calculating Baseball Stats

At first glance, baseball statistics may seem needlessly complex and confusing.  But, once you learn how to calculate these numbers correctly, it’s pretty simple.  You can identify the best, and worst, players in the game based purely on the statistical numbers they produce. This will make it easy for you to handicap baseball.  Let’s take a look at a multitude of different baseball statistics, how they are calculated, and who some of the greats are in each category.

Batting Average

Baseball is one of the few sports in which you can fail to achieve your goal 70 percent of the time, and still be considered a pretty good hitter. In the history of Major League Baseball, only 204 players ended their careers with a batting average over .300. So how do you calculate this average?

Formula: Hits divided by At-bats, rounded up to the third decimal place

Ty Cobb, notorious for his hustle, determination, and outright anger on the diamond, is Major League Baseball’s career batting average leader, with a .366 lifetime mark. Even more interesting is the fact that, if you ask most baseball historians, they would tell you Cobb isn’t the greatest hitter of all time. That honor would go to Ted Williams, the Boston Red Sox great who hit .344 in his career, which included a season in which he batted .406. To put that into perspective, Carl Yastremski, another Red Sox legend, once led the American League with a .301 batting average.

On-base Percentage (OBP)

Batting average is just one way to calculate a players effectiveness at the plate. Another is by looking at their on-base percentage (OBP).  OBP not only factors in hits, but also walks, hit by pitches, and sacrifices. On-base percentage rewards players who not only get a lot of hits, but who also draw a lot of walks.

Formula: (Hits + Walks + Hit By Pitch) divided by (At-bats + Walks + Hit By Pitch + Sacrifices)

When Barry Bonds was dominating baseball during the early 2000’s, he was doing so by hitting home runs and drawing walks. Since teams were so afraid of giving up home runs to Bonds, they decided to intentionally walk him. This led to Bonds putting up astronomical on-base percentage numbers from 2001 to 2004. His .609 on-base percentage in 2004 is the Major League record, second only to his own .581 mark set in 2001. To once again put this number into perspective, Todd Helton ranked second to Bonds in 2004 with a .468 “OBP”.

Home Run Ratio

This statistic is very simple to calculate. You simply take the number of at-bats a player has, and divide it by the number of home runs they have hit.

Formula: At-bats divided by Home Runs

It’s no surprise that legendary sluggers like Mark McGwire (10.61), Babe Ruth (11.76) and Barry Bonds (12.92) top the career home run ratio leaders list.

Slugging Percentage

Average is used to determine a batters total number of hits.  On-base percentage is used to easily tell how many times they reach base in general.  Now, slugging percentage is a measure of how many total bases a batter creates with their bat. A single is one base, a double is two, triple is three, and a home run is four. The more total bases you rack up, the higher your slugging percentage will be.

Formula: Total number of bases divided by At-bats

A slugging percentage over .500 is considered very good. Typically, the yearly slugging percentage leaders will finish slugging .600 or better. During his record breaking 73 home run season in 2001, Barry Bonds set the single season slugging percentage mark with a ludicrous .863 output.

Isolated Power

One of the more advanced batting statistics, Isolated Power exists as a way to measure each batters raw power output. Isolated Power is calculated by subtracting the hitters slugging percentage from their batting average.

Formula: Slugging Percentage minus Batting Average

As with Home Run Ratio, the career Isolated Power leaders is a who’s who of Hall of Fame sluggers. Babe Ruth, the most famous power hitter of all time, is the king of Isolated Power with his .348 ISO

On-base plus Slugging (OPS)

OPS is arguably the best way to measure a hitters value, since it combines the crucial aspects of getting on base (as in, not making an out) with hitting for extra bases.  It’s one of the stats I really feel like can give you an edge with your MLB betting.

Formula: On-base percentage plus Slugging percentage

An OPS over .800 is typically considered pretty good for most players, with premiere sluggers routinely going over .900 and sometimes breaking single digits. The “Sultan of Swat” Babe Ruth holds the career OPS high mark at 1.16

Earned Run Average (ERA)

Since baseball is a 9 inning game, some stats take that into account. ERA is one of them. Primarily used as a tool to compare starting pitchers, ERA tries to calculate how many runs a pitcher would give up in a game, assuming they pitched all 9 innings.

Formula: 9 multiplied by (Earned Runs Allowed divided by Innings Pitched)

In the modern era, an ERA under 3.50 is considered above average for a starting pitcher. Only three players in baseball history have finished their careers with an ERA under 2, but they all played in the late 1800’s and early 1900’s during what is commonly referred to as the Dead Ball Era.

Walks and Hits per Innings Pitched (WHIP)

The WHIP statistic measures a pitchers ability to limit the number of base runners they allow. While some pitchers may not give up a lot of hits, their walk totals will inflate their WHIP. In the eyes of WHIP, a line drive single and a 10 pitch walk are exactly the same.

Formula: Walks + Hits divided by Innings Pitched

For starting pitchers, a WHIP at 1.20 or lower is very good. Since relief pitchers find themselves in situations in which one additional base runner could turn the tide of a game, managers want to find relievers with a WHIP of 1.00 or lower. Mariano Rivera, the best relief pitcher of all time, finished his career with a 1.00 WHIP.


One of the most complex statistics to determine, a save is given to the pitcher on a winning team who meets certain criteria. That criteria is:

  • He finishes the game
  • He is not the winning pitcher
  • He pitches at least a third of an inning
  • He fulfills one of the following criteria

1. He enters the game with a lead of no more than 3 runs and pitches one full inning
2. He enters the game with the tying run either on base, at-bat, or on deck.
3. He pitches at least 3 innings.

In the modern game of baseball, the vast majority of saves are performed by relief pitchers called “closers”, who will pitch the final inning of a game if their team is up by 3 runs or fewer. Mariano Rivera is the all time saves king with 652.


If a relief pitcher can’t get a save, the next best thing is a hold. A hold occurs when a reliever enters the game in a save situation, records at least one out, and leaves the game with his team still ahead. However, his team must hold their lead while he’s in the game in order for him to receive credit for a hold. Holds are a relatively new stat that isn’t officially kept by Major League Baseball.

You might also be interested in our wagering glossary if you find yourself unfamiliar with some of the terms gamblers use.