In baseball statistics, earned run average (ERA) is the average of earned runs allowed by a pitcher per nine innings pitched (i.e. the traditional length of a game). It is determined by dividing the number of earned runs allowed by the number of innings pitched and multiplying by nine.

Earned run average represents the number of earned runs a pitcher allows per nine innings -- with earned runs being any runs that scored without the aid of an error or a passed ball. ERA is the most commonly accepted statistical tool for evaluating pitchers. The formula for finding ERA is: 9 x earned runs / innings pitched.

防禦率 （英語： ERA, earned run average），又稱 自責分率，是 棒球術語，指 投手 平均每場球所失的 自責分，分值越低则代表投手表现越好。 投手因為被打 安打 或 四壞 而讓人上壘（因為 野手 失誤 而上壘的不算），然後又因任何原因讓這上壘的人回來 得分 （就算換投手，惟壘上那人還是原投手要負責的），此時的得分則為自責分。 若某野手失誤讓人上壘，而該守備足以結束此局者，之後只要有 失分，都不算自責分；因為若沒發生失誤，此局可以提早結束，所以不是投手 …

投手防御率又称自责分率，指投手平均每场球所失的自责分。 投手因为被打安打或四坏球而让人上垒（因为野手失误而上垒的不算），然后又 因任 何原因让这上垒的人回来得分（就算换投手 可是垒上那人还是原投手要负责的），这个分就算成自责分 [1]。 若两人出局后，某野手失误而让人上垒，之后只要有失分，都不算自责分；因为若没发生失误，此局可以提早结束，所以不是投手的错。 举例来说，假设国民队投手甲本球季累计主投102又2/3局 (102局又2人次)，责失31分，所 …

May 22, 2023 · Earned Run Average, or ERA, lies at the heart of evaluating a pitcher's effectiveness in a baseball game. Developed by English-American sportswriter and statistician Henry Chadwick, ERA measures the number of earned runs allowed per nine innings pitched.

If you're a baseball fan, this ERA calculator is right in your ballpark. It finds the value of the earned run average – a metric that measures a pitcher's effectiveness in a much more accurate way than a simple win-to-lose ratio (see our winning percentage calculator in that case).

May 24, 2023 · ERA is a baseball acronym that stands for Earned Run Average. It is a metric that measures the number of earned runs a pitcher allows per nine innings pitched. ERA works by factoring in the number of innings pitched and the total …

Earned runs is the key counting statistic used in ERA, the most widely accepted barometer of a pitcher's success. If there are no errors or passed balls in a given inning or game, all the runs in that inning or game are earned runs.

May 15, 2022 · A pitcher's Earned Run Average (aka ERA) is a primary measure of his success. It is similar, but not identical to, run average. It is expressed as an average number of opponents' earned runs scored per notional nine inning game: ERA = (Earned Runs Allowed * 9) / …