How long is ONE generation?

[voan2]

5 years? 10 years? or 20 years?...

[Quizmonster]

It is generally reckoned at 30 or 33 years. 33 has the advantage of making a century three generations for ease of counting back.

[geofbob]

Quizmonster's 30 years is right if the word is being used about generations of human beings or in a general historic sense - eg "WW2 took place two generations ago". But when used in respect of animals, machines etc it can be a much shorter period - eg "every year we see a new generation of computers".

[inachis]

the time taken to generate new offspring so humans become fertile at 16 years say but can have children ostesibly untill they die (men) generations overlap so for historical purposes a lifetime three score and ten is a generation eg generations of men