Population Growth from Creation to Noah's Flood

Genesis chapter five provides a basis for estimating the world population at the time of Noah's Flood. The large families and long lifespans described cause the population to grow rapidly. How large could that population be?

Parameters:
Seven parameters determine how fast population grows. They are:

The Number of Years between Creation and the Flood
The Average Mother's Age when her first child is born
The Average Number of Children per Family
The Number of Years between Children
The Percent Infertile or Who Never Marry
The Average Age of Death
The Maximum Sustainable Population of Earth

Parameters can be estimated using information in Genesis chapter five, logic, and information from modern society. The parameter detail pages provides assistance in determining appropriate parameters. Parameter Details

Calculation:
Once you have determined appropriate parameters, enter them in this table to calculate the population. All the parameters have default values, but please change them to what you think is realistic.

Minimum Population
To establish a minimum population select parameters that minimize the growth and yet fit the guidelines of Genesis chapter five. These parameters would produce a minimum population at the time of the flood:

The average woman is 66 years old when she gives birth to her first child;
The average family has only five children;
Eight years pass between the births of children;
Four percent are infertile or never marry; and
The average age of death is 850.

These parameters provide a lowest estimate of the population at the time of the flood. Using them the population would be about 195 million people at the time of the flood. A more resonable, yet low estimate would have a mother 65 years old having six children six years apart, three percent are infertile, and the average age of death is 900. This would produce a population of nearly 15 billion people at the time of the flood.

Summary
The population at the time of the flood was huge. Best estimates would put it at more than the population of the world today. The global flood was a cataclysm that destroyed a population larger than today's population. Why would God destroy so many people including young children? There is a very important reason. That reason is intimately tied to the question, "Who were the sons of God and the daughters of men?"

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Years from Creation to Flood (~1656 years in Masoretic text):
Age of mother when first child is born: (likely older since they lived so long)
Average number of children per family: (named son, other sons and daughters => 5+)
Years between children: (likely longer than today's average)
Percent infertile or never married: (likely small since few genetic problems)
Average age of death: (most men listed lived over 900 years)
Maximum sustainable population (in billions): (the earth can produce food for only so many)