Earned run average

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) / Innings Pitched

All Time Leaders
Span	Player	Total	Notes
Career	Ed Walsh	1.82
Season	Tim Keefe	0.86	1880
Season (since 1920)	Bob Gibson	1.12	1968
NPB Career	Hideo Fujimoto	1.90
NPB Season	Hideo Fujimoto	0.73	1943
KBO Career	Dong-yol Sun	1.20
Cuban Career	José Antonio Huelga	1.50	Post-Revolution
AAGPBL Career	Jean Faut	1.23
AAGPBL Season	Lois Florreich	0.67	1949
MLB Career minimum 1000 innings

See Also

• List of Major League Baseball ERA champions