In baseball statistics, earned run average (ERA) is the mean of earned runs given up by a pitcher per nine innings pitched (i.e., the traditional length of a game). It is calculated by dividing the number of earned runs allowed by the number of innings pitched and multiplying by nine. Runs resulting from defensive errors (including pitchers' defensive errors) are recorded as unearned runs and are not used to determine earned run average.
This is a list of the top 100 players in career earned run average, who have thrown at least 1,000 innings.
Ed Walsh holds the major league earned run average record at 1.816. Addie Joss (1.887) and Jim Devlin (1.896) are the only other pitchers with a career earned run average under 2.000.