How To Calculate Earned Run Average

Also, if there is an error and runner(s) score, the number of Earned Runs should only be the number of runs that would have scored had the fielding been made cleanly.

The formula:

With a zero in the denominator, this result is undefined since a number can NEVER be divided by zero. Even this poor win/loss record did not stop the Ryan Express from finishing in the Top 5 voting for the Cy Young Award that year. It doesn’t matter how many innings pitched because if he never gave up a single earned run the numerator will always be zero and zero divided by ANY number is zero.

Then using our formula:

Many people get confused by a pitcher having allowed Earned Runs but without retiring a batter. Let us use a real example and view Nolan Ryan’s stats for the 1987 season:

(0 ER x 9) / IP = 0.00.

Ryan actually led the league in ERA in 1987 with 2.76. This shows why ERA can help provide an explanation for a seemingly dismal season and to allow for better decision making.

If a runner pitches a shutout for a game or season, it is easy to see that his ERA is 0.00.

If the Earned Runs are not given to you, or you are tallying for a game then just remember, the pitcher responsible for placing the runner on base gets saddled with the Earned Run if that baserunner scores – even if the responsible pitcher is no longer in the game. He also led the majors with 270Ks that year, but finished with an 8 –16 Record! The poor hitting Houston Astros gave his efforts little support. This will ensure an accurate calculation. His ERA?

(3 ERs x 9) / 0 IP = undefined

Baseball more than any other sport is a game of numbers. For example, in his debut Wild Thing allows 3 runs on 6 walks and fails to retire a single batter before being yanked by his angry manager and shoved on a bus back to the bush leagues. These statistics allow fans to make comparisons amongst players and even allows for comparisons between current players and all-time greats. His ERA shows just how good he was, but received little help. In this case, Ryan pitched 211 complete innings and 2 outs which is 2/3 inning or .667 making his actual innings pitched 211.667. Given a pitcher’s earned runs, you multiply by 9 and then divide by the total number of innings pitched. The method of how to calculate earned run average is an easy formula that will help your decision making in fantasy baseball leagues drafts, sports betting or acting as statistician for your neighborhood little league team.

(65 x 9) / 211.667 = 2.763 or 2.76

since ERA is always shown as rounded to two decimal places.

**It is common to represent partial innings as .1 or .2 to symbolize the number of outs, but when the math is performed these should be converted to proper decimals. Just as a batting average is a great measure of hitter effectiveness, a pitcher’s earned run average (ERA) is a great gauge of a pitcher’s likelihood of success against an opposing team. So grab your calculator and get to calculating! The baseball cards are on the shelf and the season is about to begin!

(Earned Runs x 9) / Innings Pitched

. However, from calculus days, this result as the denominator gets closer and closer to zero is infinity and normally the pitcher’s ERA will be represented by the infinity symbol (∞).

Earned Runs = 65

This simple formula does it all. Likewise, as another example, 15.1 innings would be 15.333 innings when properly factored.

Once you master earned run average, you can tackle hitting stats like calculating batting average and calculating slugging percentage, too

Daisy Henry

Daisy Henry

This author is a HUGE fan of Sports Betting
Daisy Henry

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