What is ERA in Baseball?

Statistics, like batting averages, have always been an integral part of MLB (Major League Baseball) and even baseball in general. One such statistic is the ERA, which is a particularly important stat for pitchers. So, what is ERA in baseball and how do you calculate it? This article attempts to answer these questions, along with a few others.

What is ERA in Baseball?

ERA is an abbreviation for ‘Earn, Run, Average’, and was created by the English-American writer and statistician, Henry Chadwick. Chadwick also contributed to a number of other aspects of baseball, including batting average, box score, and using the letter ‘K’ to abbreviate a strikeout. Due to his contributions to the sport, Henry Chadwick is also called the ‘Father of Baseball’.

How Does the ERA Stat Work?

Any run that is scored directly off a pitch rather than as the result of a fielding error or some other factor is referred to as an ‘earned run’. Conversely, any run not scored as a direct result of the pitch, is categorized as an ‘unearned run’.

Naturally, then, the aim of a pitcher is to prevent the opposing team from scoring earned runs. The ERA, in this regard, is an average of the number of earned runs that a pitcher concedes in a typical nine-inning game. This is why the ERA is a very important stat for any pitcher – it is one of the clearest indicators of how well a pitcher is achieving their objective.

So, to simplify, the ERA shows us the average number of earned runs that a pitcher is conceding during the nine-innings of a typical baseball game. Despite giving a ‘ballpark’ figure, the ERA is pretty accurate at gauging the average performance of a pitcher over the course of a season.

How Do You Calculate ERA?

The ERA calculation is fairly straightforward, and consists of two steps:

Step 1: Divide the number of earned runs conceded, by the number of innings in which a pitcher has pitched.

Step 2: Take the answer to the above calculation, and divide it by 9, which is the total number of innings in a typical baseball game.

Following the above two steps will give you the average number of earned runs that a pitcher concedes during a nine-inning baseball game. The ERA is usually calculated to two decimal places, and can be calculated for an entire career or a particular season, depending upon your analysis requirements.

To make the calculation clearer, let us assume that a pitcher has pitched in 120 baseball innings so far, and have conceded a total of 60 runs, 50 of which were earned. To calculate the ERA for this pitcher, you will divide 50 (number of earned runs conceded) by 120 (the number of innings in which the pitcher has pitched so far). The answer will then be multiplied by 9 (the number of innings in a typical game of baseball).

So, the calculation would go something like:

(50/120) x 9 = 3.75

The ERA for this pitcher is 3.75.

Should Pitchers Aim for a Higher or Lower ERA?

Like we mentioned, the primary aim for any pitcher is to prevent the other team from scoring earned runs. A lower ERA will mean that a pitcher has conceded fewer earned runs over the course of a season or their career. For this reason, pitchers should aim to keep their ERA as low as possible.


In modern-day baseball, pitchers should aim for an ERA of at least below 4.00. An ERA of 3.50 or below is considered excellent, while an ERA of 2.00 or below is quite rare, and is indicative of a pitcher with exceptional skill and talent. An ERA of 5.00 or above is considered quite poor, and pitchers with such ERAs either only either pitch in blow-out matches, or are relegated to the minor leagues.

Who is the Player with the Lowest ERA Ever?

If we talk about a one-season ERA, Tim Keefe owns that record with an ERA of 0.86. He achieved this feat during the 1880 season, when he was representing the National League Troy Trojans.

Another player with a single-season ERA of below 1.00 is the left-handed pitcher, Dutch Leonard. He achieved this ERA in 1914, while playing in the American League.

Players with Great Career and Seasonal ERAs:

Ed Walsh with 1.79 holds the record for the lowest career ERA. Walsh’s career spanned over a period of seven years (1906-1914).

Bob Gibson, too, had an impressive ERA of 2.91. However, it is important to remember that Gibson had a significantly longer career: he represented the St. Louis Cardinals for seventeen years – the entirety of his career. In 1968, Gibson’s best season, he hit an ERA of 1.12.

Dazzy Vance, who has the unique distinction of being the only pitcher to have led the Nation League strikeouts for seven straight seasons, achieved an ERA of 2.16 in the 1924 season.

Babe Ruth, the legendary baseball player known for his slugging, was also an excellent left-armed pitcher. He had a surprisingly low career ERA of just 2.28.

In the modern era, Pedro Martinez is probably an excellent example. The Red Sox pitcher, who also made it to the All-Star team on eight occasions, had a career ERA of just 2.93. His lowest seasonal ERA came in 2000, where he conceded at an average of just 1.74 per nine innings. 2.93 is the sixth-lowest ERA for any pitcher who has pitched in 2,500 innings or more.

Our Final Thoughts:

In conclusion, the ERA is an excellent statistic to evaluate the performance of a pitcher, as it gives a clear idea about the number of earned runs that a pitcher is conceding during a nine-innings game. For instance, the ERA statistic is a far better measure of a pitcher’s effectiveness than the number of wins earned by the pitcher.  The ERA stat is best used in tandem with the WHIP (Walks and Hits per Innings Pitched), which gives you an idea about the hits and walks that a pitcher gives up in each inning.

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