ERA Calculator
Calculate a pitcher's earned run average from earned runs and innings pitched, with partial innings handled.
Enter partial innings in baseball notation: 6.1 = 6⅓, 6.2 = 6⅔.
How it works
Earned run average tells you how many earned runs a pitcher gives up per nine innings — a full game's worth. The formula is earned runs × 9 ÷ innings pitched, so three earned runs over six innings works out to a 4.50 ERA.
Only earned runs count. Runs that scored because of an error or a passed ball are 'unearned' and left out, since ERA is meant to isolate the pitcher's own performance from the defense behind him.
Innings pitched use baseball's decimal quirk: .1 means one out and .2 means two outs, not tenths of an inning. Enter 6.2 and we read it as six and two-thirds innings before doing the math.
Frequently asked questions
What counts as a good ERA?
It shifts with the era of the game, but in modern baseball an ERA under 3.00 is excellent, around 4.00 is roughly league average, and above 5.00 is a struggle.
How do I enter two-thirds of an inning?
Type it as 6.2. In baseball notation the digit after the decimal is outs recorded, so .1 is one out and .2 is two outs. The calculator converts that to thirds before dividing.
What makes a run 'earned'?
A run is earned when it scores through hits, walks, and other things the pitcher is responsible for. If a fielding error or passed ball let the run score, it's unearned and doesn't count toward ERA.