If you are big into the baseball scene, you might have heard the term “infinite ERA” thrown around, but the thing that is confusing about this term is ERA is a statistic that tracks how many earned runs a pitcher gives up for every nine innings pitched. It doesn’t really make sense how a pitcher can give up an infinite number of runs. What is infinity ERA?

**Infinity ERA, also known as infinite ERA, is when a pitcher allows one or more earned runs without recording a single out. ERA is calculated by dividing earned runs by innings pitched and multiplying by 9, but if no outs are recorded then you would be dividing by 0, which equates to infinity.**

Still wondering about how infinite ERA works, or have other questions about it? Keep reading below to find out more about infinite ERA in Major League Baseball, and how a few players have had this title bestowed upon them.

Learn more about what is an ERA by reading A Beginner’s Guide to Baseball’s ERA Statistic.

Article Contents

## How is it Possible for an ERA to Be Infinite?

Initially, the idea of an infinite ERA might seem confusing and you might wonder how it’s possible for a player to achieve such a title. First, we’ll need to know how to calculate a pitcher’s ERA. I’ll explain it at a high level below, but read my article on the 3 steps to calculating a pitcher’s ERA to learn more about the formula for calculating ERA.

Here’s how it works: earned run average, often shortened to ERA, is a common pitching statistic used in baseball and this number has a specific formula for being calculated.

**As we’ve previously established, a pitcher’s ERA is calculated by dividing the number of earned runs by the number of innings pitched by that pitcher, and that number is then multiplied by 9. However, if a pitcher takes the mound and does not record an out, they have technically pitched 0 innings.**

This is because the Innings Pitched (IP) statistic is measured in thirds – a pitcher earns one-third of an inning pitched for each out recorded. If a pitcher records no outs, they have pitched 0 innings.

**On top of that, there are instances where pitchers give up a run without acquiring an out.** When this occurs and you try to find a pitcher’s ERA, you would have to divide the total number of earned runs by 0, which equals “infinity” or “undefined”, depending on how you’re using the number. In this case, ERA would be classified as “infinity”.

So, whether you’re measuring a pitcher’s ERA in terms of their season or in terms of a single appearance, it’s possible to get an infinity ERA when a pitcher gives up one or more earned runs and fails to record a single out.

And remember, there is a difference between an unearned run and an earned run. Read more about what makes a run an earned run.

## How to Display an Infinite ERA

**While there is not a universally accepted way to display an infinite ERA, the most common ways include using “INF”, “0.00”, an infinity symbol (pictured above), or simply leaving the ERA field blank.**

For example, in the 1953 season, Ed Blake pitched for the Cinncinatti Reds and he ended that season with an infinite ERA. If you look at Ed Blake’s 1953 stats on Baseball Almanac, you’ll see they used an infinity symbol for that season’s ERA.

The MLB leaves his ERA blank for that same season, FanGraphs has his ERA at “0.00”, and Baseball-Reference has his ERA listed as “inf”.

## Are Infinite ERA’s Common?

Infinite ERAs are considered to be unique anomalies in pitching, and there is a list with the names of all of the pitchers who have earned this title in a single season. You can find that list of Major League pitchers on the Baseball Almanac website.

**At the time of this article, there were a total of 62 pitchers in all of baseball’s history to end a season with an infinity ERA.** And on this same list of pitchers who are members of the Infinite ERA Club, there are pitchers whose names are bolded, indicating their earned run average for their overall baseball career is infinite.

**The first recorded instance of a pitcher getting an infinite ERA was Dave Pierson in 1876. Pierson played for the Cincinnati Red Stockings.**

While infinite ERAs are not common, they are most commonly associated with the start of the MLB season. This is because the ERA stat is generally calculated based on a pitcher’s entire season, but pitchers do not have a lot of statistics towards the beginning of a season.

So at the beginning of a baseball season, it is more common to see pitchers with an infinite ERA because it is more likely to see pitchers give up runs without acquiring outs. But as the season goes on, those pitchers play in more games and eventually erase any infinite ERA statistic they may have had.

## What is Considered a Good ERA?

In baseball today, an ERA under 2.00 is considered rare and outstanding. An ERA between 2.00 and 3.00 is excellent and only achieved by the best pitchers in a league. An ERA between 3.00 and 4.00 is still great and considered above average, and an ERA between 4.00 and 5.00 is average and most pitchers fall somewhere in that range. An ERA above 5.00 is considered below average.

**Knowing these general ranges for ERA, we can conclude that a pitcher who has an infinite ERA falls well below the average ERA for pitchers in the MLB.** This is because infinity ERA is the highest ERA a pitcher can achieve and pitchers prefer to have a low ERA rather than a high ERA.

For a more in-depth analysis of what makes a good ERA (using pitching statistics from the MLB), read my previous article to learn more about what is a good ERA in baseball.

## Limitations of the ERA Statistic

Some people are not a fan of using ERA as a statistic and the idea of a pitcher having an infinity ERA is just another example of why they don’t like this stat.

**The ERA is not the best at measuring the success of relief pitchers, since relief pitchers often play for part of an inning. This is especially true for specialty relief pitchers, like set-up pitchers and closers.**

Relief pitchers will often have a lower ERA than starting pitchers because they tend to exert all of their energy over a shorter period of time rather than conserving and spreading it over the course of an entire baseball game.

It’s important to keep in mind that ERA is not always a perfect measure of a pitcher’s skill since the trade-off between starting and relief pitchers in games can complicate how the statistic is calculated for each type of pitcher.

**The infinite ERA is a fun statistical anomaly that occurs in baseball, but keep in mind the limitations of ERA statistics as you evaluate various baseball players.**

However, some people really like using ERA to judge pitchers. To help you decide if you like the idea of using ERA as a statistic, read more about the 4 pros and 4 cons of using ERA as a stat.

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