Answer
The Bible does not explicitly say how long it took Noah to build the ark. However, there are a few milestones in Noah’s construction of the ark that help us make some reasonable estimates as to how long the process took.
All we have to go on is the biblical data. When Noah is first mentioned in Genesis 5:32, he is 500 years old. By the time Noah entered the ark and the flood began, Noah was 600 years old (Genesis 7:6). Noah received the command to build the ark in Genesis 6:14.
The time it took to build the ark would therefore depend on how much time passed between God’s instruction in Genesis 6 and the rainfall in Genesis 7. This could not have been more than 100 years when we compare these two verses:
“After Noah was 500 years old, he became the father of Shem, Ham and Japheth” (Genesis 5:32).
“Noah was six hundred years old when the floodwaters came on the earth” (Genesis 7:6).
Some scholars believe that it took Noah 120 years to build the ark, based on the mention of that time span in Genesis 6:3: “Then the Lord said, ‘My Spirit will not contend with humans forever, for they are mortal; their days will be a hundred and twenty years.’” If this view is correct, then it would seem to imply that either Genesis 5:32 or Genesis 7:6 (or both) rounds Noah’s age to the nearest 100 years. Alternatively, if neither of Noah’s recorded ages is rounded, we may conclude that God decided to extend His mercy for 120 years and then 20 years later revealed His plan to Noah.“Noah was six hundred years old when the floodwaters came on the earth” (Genesis 7:6).
So, we can say that it took Noah 100—120 years to complete the construction of the ark. We do not have enough information to say anything more precisely than this.
