College ERAs - based on 7 or 9 innings?

NCAA Rule 10, Section 29

d. To determine a pitcher’s earned-run average, multiply the earned runs allowed by nine and then divide by the number of innings pitched;
Note: The statistician may choose to compute earned-run average by multiplying the earned runs allowed by 27 and then dividing by the number of outs recorded (innings pitched times three). Earned-run averages must be based on nine innings.

Thanks. I can't find anything about the computation of NAIA and JUCO ERAs.

Doesn't NAIA specify OBR? I can't remember for sure, and could be wrong on that.

They all use 9 innings(27 outs)

If you pitch 14.2 innings you turn it into outs 42 +2.
9 x 3 outs = 27 outs. Divide 27 x 44 mutiply by 4 ers = 2.44 era.

The basic formula is simple. Earned runs per inning, times standard number of innings in a game. That gives you the average number of earned runs you would expect to see that pitcher yield in a complete game, which is the definition of ERA. A pitcher who pitches one inning and gives up one earned run would have a Little League ERA of 6.00, a high school ERA of 7.00, an adult ERA of 9.00.

But JUCOs and NAIAs play both 7 and 9 inning games.
Very often two 7 inning events.

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What is pitcher's ERA if he gives up 1 earned run and his team wins in 5 innings by virtue of a mercy (10 run) rule?
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Similarly, does it count as a "No-Hitter" or "Perfect Game" if such game ends in less than the normal 7 or 9 innings due to a mercy rule or rainout?

The 7-inning games you're talking about, e.g., for doubleheaders, do not affect the fact that the standard game length is 9 innings, so you use 9 in calculating the ERA.

You don't calculate ERA game by game, but rather, cumulatively over the season, so whatever the length is at your level, you use that number throughout your stat sheet. If an adult pitcher gives up 1 earned run in 5 innings and that's all he ever pitches, his ERA is going to be 1.80. But that's only if he never pitched before and never pitches after. There's absolutely no point in determining what his ERA was for the one day. The whole point of ERA is to gather a statistic over a period of time and try to have something you can compare to others on an "apples to apples" basis.

If a game ends early, you do get credit for a no-hitter or perfect game but you'd probably note the shortened game in the process. In any event there is no statistical category for these, they just go into your team's record book. The stats compile into the season stats same as if your pitcher had been removed prior to completing a 9-inning game.

Mid is correct.

Don't always expect the ERA to be correct. My son gains an er out of no where. Last year he gained 2.