Understanding Earned Run Average (ERA): Calculation & Explanation

Question
Really dumb question I'm embarrassed to ask:  how is earned run average
calculated?

Thanks.

Ken

Answer
Ken,

Here it is:

ERA = (9 x Earned Runs Allowed)/Innings Pitched

So, a pitcher who gives up 4 earned runs when pitching 8 innings:

9 x 4 / 8 = 4.50 ERA

If they give up 50 runs in 100 innings pitched:

9 x 50 / 100 = 4.50 ERA

Hope this helps!

Brian