Noah likely took between about 40 to 75 years to build the ark, according to various interpretations of biblical texts and traditions.
- The Bible states Noah was 500 years old when he had his sons and 600 years old at the time of the flood (Genesis 5:32; 7:6). Since God instructed Noah to build the ark after his sons were born and married, this suggests a building period of roughly 40 to 75 years
- Some sources propose a maximum of 75 years, considering the time needed for Noah's sons to grow and marry before the flood, and the complexity of the ark's construction
- Other traditions and commentaries vary widely, with estimates ranging from as little as 5 years (Sefer Hayashar) to as many as 120 years, though the 120 years mentioned in Genesis 6:3 likely refers to the period God gave humanity before the flood, not the ark's construction time itself
- The ark's construction was a substantial engineering project requiring significant skill and manpower, possibly involving help beyond Noah and his family
In summary, the most reasonable biblical-based estimate is that Noah took several decades, approximately 40 to 75 years, to build the ark before the flood began.
