How long is 18 generations?

Answer 1

The true length of one generation is variable, as it is the time from the birth of one person to the birth of that person's child. As a rule of thumb, 25 years has often been used as an average number, but with many in the western nations having fewer children later in life, some are beginning to use bigger numbers for modern generations. For generations after the middle of the 20th century, some have proposed using 33 years.

If a generation is 25 years, then 18 generations is 450 years.

If a generation is 33 years, then 18 generations is 594 years.