How Long Did It Take Noah to Build the Ark? Up to 100 Years, by Age 600

Genesis does not say how long Noah took to build the ark, but its ages set the frame: if he began after his sons were born, he had at most about 100 years, and finished by the time he was 600. He became a father at 500, and Augustine took the next hundred years as the building time.

The other figure often heard, 120 years, comes from Genesis 6:3. The Jewish commentator Rashi pictured Noah at work on the ark for all of that time, and Tim Chaffey of Answers in Genesis calls it “the common view”, though he himself sets the limit at about 75 years and thinks it may have been far less. Each answer rests on the same handful of verses, read in a different way.

How old was Noah when he built the ark?

Between 500 and 600 if the work began after his sons were born; from 480 if it took the 120 years of Rashi’s reading. Genesis fixes the two ages that frame it: “Noah was five hundred years old: and Noah begat Shem, Ham, and Japheth” (Genesis 5:32), and “Noah was six hundred years old when the flood of waters was upon the earth” (Genesis 7:6). The ark was ready before then: God gave Noah seven days’ notice, “For yet seven days, and I will cause it to rain upon the earth” (Genesis 7:4), and Noah and his family went in “because of the waters of the flood” (Genesis 7:7).

By Noah’s own age, the years around the ark run like this. Several of the ages are worked out from the numbers in Genesis 5 and 11 rather than stated.

How old was Noah when God told him to build the ark?

Genesis does not give his age at that moment, only the order of events. It names Noah’s three sons twice, at the end of chapter 5 and again as the flood story opens: “And Noah begat three sons, Shem, Ham, and Japheth” (Genesis 6:10). Only after that does God say, “Make thee an ark of gopher wood” (Genesis 6:14). Read in that order, the command came after Noah turned 500. Augustine read it so: “Noah was five hundred years old when God told him to make the ark, and six hundred when he entered the ark; which shows that the ark was made during one hundred years.”

The Jewish commentator Rashi did not hold to the order of the verses. Explaining Genesis 6:3, he reminded his readers that “there is no ‘earlier’ or ‘later’ in the Torah,” meaning that Scripture does not always tell events in sequence, and he placed God’s decree “twenty years before Noah had any children,” that is, when Noah was 480.

Noah became a father at 500 and saw the flood at 600: when did he start?

Somewhere in that century, if the order of the verses is the order of events, and one more verse narrows the guess. When God gives Noah the plan of the ark, he adds a promise: “thou shalt come into the ark, thou, and thy sons, and thy wife, and thy sons’ wives with thee” (Genesis 6:18). Some readers take this to mean the sons were already married when the work began. Answers in Genesis builds its estimate on that reading. Its writer Tim Chaffey supposes Ham was born when Noah was about 505 and that the sons married at 20 or older, which would make Noah about 525 before the last wedding and leave “a maximum of about 75 years” for the ark.

The promise looks ahead, though. “Thou shalt come into the ark” tells Noah who will be saved, not when his sons took their wives, so the verse can also fit a start soon after Noah turned 500. Bodie Hodge, writing for Answers in Genesis in 2010, read the verse as Chaffey does but began from Japheth, whom he took to be born when Noah was 500. He allowed “anywhere from 20 to 40 years” for the sons to grow up and marry, which left 55 to 75 years as “a reasonable maximum time to build the Ark.”

How long did it take Noah to build the ark?

No verse says. Four answers have been given:

The hundred-year answer was already being told in Origen’s day. A critic named Celsus had called the ark monstrous, and Origen asked where its monstrous character lay, “seeing it is related to have been a hundred years in building.” Augustine worked the figure out from Noah’s ages and, defending the ark against people who said it could not have been built, told them to “remember that the ark was an hundred years in building.”

Answers in Genesis comes at the question as builders. It built the Ark Encounter in Kentucky to the measurements of Genesis, and Chaffey writes: “Our construction period only lasted about 26 months, but we had the benefit of modern technologies and hundreds of skilled laborers.” He concludes that 75 years was “roughly the upper limit” and asks whether Noah might have done it in 20 to 25.

The New Testament does not count the years either. It remembers them as patience, God’s more than Noah’s: “the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water” (1 Peter 3:20). In the King James English, “a preparing” means that the ark was still being built.

Was it really 120 years?

Genesis 6:3 is the only 120 in the story, and it does not mention the ark: “And the Lord said, My spirit shall not always strive with man, for that he also is flesh: yet his days shall be an hundred and twenty years.” The ark first appears eleven verses later, when God speaks to Noah.

Rashi joined the two. He asked why God, who had many ways to save Noah, gave him such a heavy task, and answered: “So that the men of the generation of the Flood might see him employed on it for 120 years and might ask him, ‘What do you need this for’?” Noah would then tell them a flood was coming, in the hope that they would repent. The Midrash Tanchuma orders it differently: God “forewarned the generation of the flood to repent its misdeeds for one hundred and twenty years,” and only “When they refused to repent” did he command the ark. Then Noah plants cedars, tends them “till they grew large,” and cuts them into timber while his neighbours laugh. The Talmud remembers them calling out, “Old man, why are you building this ark?” (Sanhedrin 108b).

Chaffey reads the verse in its own setting, the passage about the sons of God and the giants that opens Genesis 6, and concludes that it “has something to do with the sons of God and the Nephilim rather than the construction of the ark.” Hodge’s earlier article for the same ministry called the 120 years “a countdown to the Flood” but still found no building time in them. Augustine kept the two apart: for him the 120 years were God’s warning before the flood, and the building took a hundred.

What does Genesis 6:3 mean by 120 years?

Christians and Jews have read the verse in two ways: as a time of warning before the flood, or as a new limit on the length of human life.

The first reading is very old. A Jewish translation of Genesis, the Targum attributed to Jonathan ben Uzziel, renders the verse: “Behold, I will give them a prolongment of a hundred and twenty years, that they may work repentance, and not perish.” Rashi has God say: “For 120 years I will be long-suffering with them, and if they repent not I shall bring a flood upon them.” John Calvin agreed that the words refer “not to the private life of any one, but to a time of repentance to be granted to the whole world.” The International Standard Bible Encyclopedia of 1915, reading the verse beside 1 Peter 3:20 and 2 Peter 2:5, says the warning came “120 years beforehand, and during that time Noah, while preparing the Ark, became a preacher of righteousness.” Worthington, quoted in Haydock’s Catholic commentary, judged this reading “more literal, and that God bore with mankind the full time which he promised.”

That reading has to fit 120 years into the hundred between Noah’s 500th and 600th years, and three answers have been given. Augustine said God spoke “when Noah had nearly completed his fifth century, that is, had lived 480 years,” and that Scripture rounds this to 500; Calvin made the same point. Rashi dated the warning twenty years before Noah’s sons were born. Jerome, as the Catholic commentator George Haydock reported him, held that God cut the time short: “God retrenched 20 years from the time first assigned for penance.”

The second reading takes the verse as a limit on lifespans. The notes of the New American Bible, the translation of the Catholic bishops of the United States, say that the growing wickedness of Genesis 6 “leads God to reduce the human life span,” bringing it down “to something near the ordinary life span.” Challoner’s notes in the older Catholic Douay-Rheims Bible give both meanings, the lifespan first, and then: “Or rather, that God would allow men this term of 120 years, for their repentance and conversion, before he would send the deluge.”

The long lives after the flood are the old objection to the lifespan reading. Shem lived to 600 and his son Arphaxad to 438 (Genesis 11:10–13). Augustine made the point himself: “even after the deluge we find that they lived more than 500 years.” Worthington added that anyone taking the lifespan view “must say, at least, that he did it by degrees,” though by Moses’ day “few exceeded that term.” Moses himself died at exactly that age: “And Moses was an hundred and twenty years old when he died” (Deuteronomy 34:7).

How old were Noah’s sons, and did they help build the ark?

All three were grown and married by the time the rain came. Genesis counts them into the ark on the day the flood began: “Noah, and Shem, and Ham, and Japheth, the sons of Noah, and Noah’s wife, and the three wives of his sons with them” (Genesis 7:13). “Shem was an hundred years old, and begat Arphaxad two years after the flood” (Genesis 11:10), so Shem was born when Noah was about 502 and was about 98 when the rain began.

Their order is less certain. The King James Version calls Shem “the brother of Japheth the elder” (Genesis 10:21), and translations differ on whether the elder is Japheth or Shem. Ham is “his younger son” in Genesis 9:24, which Answers in Genesis takes to mean the youngest. The English editor of Calvin’s commentary reasoned that Japheth was the first-born: Shem came when Noah was 502, so another son came before him, and that son was not Ham. If Japheth was born when Noah was 500, he was about 100 at the flood. The Book of Jubilees, which retells the story of Genesis, gives a different order: Shem first, Ham two years later, then Japheth.

Genesis does not say who worked on the ark. It gives the work to Noah alone: “Thus did Noah; according to all that God commanded him, so did he” (Genesis 6:22). Grown sons living beside their father may well have helped, but that is a reasonable guess, not something the text records. We look at that question, and how the ark was built, in who helped Noah build the ark.

How old was Noah when the flood came?

Six hundred. Genesis even gives the day: “In the six hundredth year of Noah’s life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened” (Genesis 7:11). He came out of the ark in his 601st year, when “in the second month, on the seven and twentieth day of the month, was the earth dried” (Genesis 8:14). We follow the flood’s year day by day in how long Noah was on the ark.

Noah lived on for centuries: “And Noah lived after the flood three hundred and fifty years. And all the days of Noah were nine hundred and fifty years: and he died” (Genesis 9:28–29). How Christians have understood Noah’s 950 years is a question of its own.

What did early Christian writers say about Noah’s age and the building?

Augustine took Noah’s ages as ordinary years. He rejected the idea that the years of Genesis were so short “that one of our years may be supposed to be equal to ten of theirs,” and held that it was a year of our own length “which was reckoned the six hundredth of Noah’s life.”

John Chrysostom, preaching on the Letter to the Hebrews, dwelt on the faith the building asked of Noah. Hebrews puts it in one sentence: “By faith Noah, being warned of God of things not seen as yet, moved with fear, prepared an ark to the saving of his house; by the which he condemned the world, and became heir of the righteousness which is by faith” (Hebrews 11:7). Chrysostom pictured the sky Noah built under: “the air was clear, there were no signs” of what was coming, “but nevertheless he feared.” The building itself should have warned his neighbours, and Chrysostom says it did not: they “were not brought to their senses even by the preparation.” Second Peter remembers Noah as “a preacher of righteousness” (2 Peter 2:5), and Chrysostom says what it cost him: “at that time he was laughed at; he was reviled and ridiculed; but he regarded none of these things.”

Related reading

• How long was Noah on the ark?
• How big was Noah’s ark?
• Who helped Noah build the ark?
• How old was Noah when he died?
• When did Noah live?