Genesis 7:11 (NIV, emphasis mine)

In the six hundredth year of Noah’s life, on the seventeenth day of the second month—on that day all the springs of the great deep burst forth, and the floodgates of the heavens were opened.

This seems like a really odd thing to record. And it persists throughout the narrative - further dates are given in 8:4, 8:5, 8:13, and 8:14. No other dates are recorded like this in Genesis as best I can tell. So why is there this flurry of exact dates surrounding the flood narrative? What is their importance?

  • 1
    Warm tropical climates consist of two distinct seasons: a wet period, and a dry one. I assume the author wanted to point out that the five months in question (150 days) corresponded to the rainy season (starting in the middle of the second month). As for the ten extra days added on top of the year (from 17.02.600 AN to 27.02.601 AN), they are probably a reference to the almost eleven day difference between the solar and lunar calendars.
    – Lucian
    Commented Jul 30, 2017 at 5:30
  • A 30 day month and 360 day year. Commented Sep 2, 2020 at 19:09

4 Answers 4


As you noted, the Great Flood story is detailed to even the day. The wording shows us in 3 different ways (making it indisputable) that only Noah, his wife, his 3 sons, and his sons’ wives got into the ark, and only they got out later. That point, some math, and the detail below, lead to one conclusion. A man can’t possibly become a father when his child is born; his fatherhood can only begin when the child is conceived. Otherwise, our math will be wrong, and below is just one of 3 such cases. In this case we have about 2 years to reconcile (See Reconcile about 2 years below). For the other 2 cases there is only 1.

First though, when we look at the flood’s detail in dates, spans of time, ages, etc. from an accounting perspective, we’ll see 3 different ways (making this also indisputable) that the flood’s span of time or how long Noah stayed on the ark, from when the floodgates were opened to when the land was dry again, was just beyond one year. Per Genesis 8:13-14 less Genesis 7:11, the flood lasted exactly 1 year and 10 days.

Gen 7:11 In the 600th year of Noah's life, in the 2nd month, the 17th day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened.

Gen 8:13-14 And it came to pass in the 601st first year, in the 1st month, the 1st day of the month, the waters were dried up from off the earth: and Noah removed the covering of the ark, and looked, and, behold, the face of the ground was dry. And in the 2nd month, on the 7th and 20th day of the month, was the earth dried. (KJV)

(601 year’s and 2nd month’s 27th day less: 600 year’s and 2nd month’s 17th day = 1 year, 10 days).

While we can’t prove that to the day again, we can confirm in two other ways the flood definitely lasted more than 1 year.

Estimate #1 is 373 days: This we could reach by focusing on water movement, mostly the two sets of 150 days.

-150 days from Gen 7:24-8:2 "The waters maintained their crest over the earth for 150 days, and then God...made a wind sweep over the earth, and the waters began to subside. The fountains of the abyss and the floodgates of the sky were closed, and the downpour from the sky was held back."

-150 then from Gen 8:3-4 "Gradually the waters receded from the earth. At the end of 150 days, the water had so diminished that, in the 7th month, on the 17th day of the month, the ark came to rest on the mountains of Ararat."

-73 additional days we would need to add. That is how much longer it took for the land to dry, the time from Gen 8:4 to Gen 8:5.
Gen 8:5 "The waters continued to diminish until the 10th month"… less: Gen 8:4 "...in the 7th month, on the 17th day of the month..." With Gen 8:5, about 270 days had gone by (9 months passed * 30 days/month = 270 days) With Gen 8:4, about 197 days had gone by ("...in the 7th month, on the 17th day of the month..." says 6 months and 17 days had passed (6 months * 30 days per month = 180 days, + 17 days = 197 days had gone by) The net of 270 - 197 is 73 days.

This estimate's total is 373 days (i.e. the 150 days + the 150 days + the 73 days = 373)

Estimate #2, which is from a 3rd way of measuring, is 382 days: This we'd reach by focusing on the diminishing waters, but passing all verses until Gen 8:5.

-271 days from Gen 8:5 "The waters continued to diminish until the 10th month, and on 1st day of the 10th month the tops of the mountains appeared." By the 10th month, 9 months had passed. [(9 months * 30 days per month = 270) + 1 day = 271 days).

-111 days is about how many we'd need to add here. Counting this way we'd have to add the 40 days before Noah opened the hatch, the 7 days before he sent the dove that returned with a leaf, the 7 days later he again sent the dove that never returned and 57 days in Noah's "601st year of Noah's life" that the water was drying. Gen 8:14 "In the 2nd month, on the 27th day…the earth was dry." (2nd month's 27th day means about 57 days have passed. (1 month * 30 days/month + 27 days = 57). The net of the 40 + 7 + 7 + 57 is 111.

This estimate # 2's total is 382 days (the 270 + the 111).

Even though we're estimating with math using 30 days/month, etc., each of the 2 estimates is definitely more than 1 year.

Next, since the span of the flood was just beyond a year, everyone’s “years old” went up by at least 1. While a child could have been born in the ark, he would have had to die in it too; that is because no child left the ark.

Reconcile about 2 years: When we combine the next 3 verses from 3 different chapters, we seem to have about 2 years to explain.

Gen 5:32: And Noah was 500 hundred years old: and Noah begat Shem, Ham, and Japheth.

Gen 7:11 In the 600th year of Noah's life, in the 2nd month, the 17th day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened.

Gen 11:10 These are the generations of Shem: Shem was 100 years old, and begat Arpachshad, 2 years after the flood. (KJV)

[If Noah was 500 years old when Shem was born and 600 at the start of the flood, then Shem would have been 100 at the start of the flood. The last verse above says he was 100 "2 years after the flood." Thus we have to explain about 2 years.
Note: At the same time, we'd be incorrect in saying "The words '2 years after the Flood' are just a mistake". If we deleted those 5 words, you can see we'd have Noah being 600 years old when the floodgates were opened; if Shem was 500 years younger, he'd have been 100 years old then (600 - 500 = 100). Since Shem begat Arpachshad when he was 100, the child would have had to be born on the ark. However, no child left the ark].

Let's temporarily assume that fatherhood begins at conception, working only with those 3 verses for now and doing the math.

Gen 5:32: And Noah was 500 hundred years old: and Noah begat Shem, Ham, and Japheth. (KJV)

(Noah was 500 years old when Shem was conceived, but Shem wouldn't be born for about 9 more months. By the time Shem was born, Noah would probably have been 501 years old. Noah would then have been 501 years older than Shem).

Gen 7:11 In the 600th year of Noah's life, in the 2nd month, the 17th day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened. (KJV)

(In the 600th year of Noah's life, his age was only 599. Again, his life began at his conception too.)

(Based on the two verses just above, Shem would have been only 98 years old when the floodgates were opened; that is Noah's age of 599 when the flood began less: the 501 years Noah was older than Shem).

Gen 11:10 These are the generations of Shem: Shem was 100 years old, and begat Arphaxad 2 years after the flood. (KJV)

(Since Shem was 98 years old when the flood began, 2 years later he would indeed have been 100 years old).

Conclusion to date: Fatherhood can only begin at conception, or the math is incorrect here and in 2 more cases. One other case is with Was or wasn’t Shem’s son Arphaxad born on the ark?, which holds different math problems using different sets of factors, excluding "2 years after the flood" for example. With that case there is only about 1 year that otherwise can't be explained. If fatherhood begins at conception, so do motherhood and childhood/life. Furthermore, that helps explain Joseph dies at about 110, with Joseph and his 110's shown twice in the final 5 verses of Genesis. In that case the author would have been writing about Joseph's life, for which counting began at conception, having 110 full years in it. Subsequently, in the final verse of Genesis and only 4 verses later, the author would have been writing about Joseph's age, for which counting began at birth yet the total years could be the same. (Otherwise, he'd be repeating someone's age at death, and Joseph would be the only one in Genesis for whom that would have been done).

  • +1 for venturing out on this. But why is it important that these dates be provided? Are you suggesting that it is part of a continuous timeline in the lineage? What does all that signify?
    – user2027
    Commented Feb 6, 2014 at 5:53
  • Two of several clues I found and used came from rounding and totaling parenthood years for everyone we can in Genesis, including Sarah, the only female in Scripture with any age given. That total came to 9,999, yet only under the assumption that parenthood begins at conception. Subsequently the actual total of parenthood years after the flood turned out to be 3,333, but again only under the same key assumption. While those totals prove nothing on their own, they were great clues toward the conclusion to date (above). Commented Feb 7, 2014 at 18:56
  • I simply see that the specific dates, along with the varying ways of counting, confirm that the length of the flood was just beyond 1 year. That led me to my "Conclusion to date" above. Now I'm going to chart the timelines. Thanks. Commented Feb 9, 2014 at 12:41
  • 4
    I don't see how any of this answers my question. "Why is Genesis careful to record the exact dates of the flood?" "Fatherhood can only begin at conception" feels like a complete non-sequitor. Am I missing something?
    – Soldarnal
    Commented Feb 26, 2014 at 5:18
  • @Soldarnal By using such detail, but especially the numbers, Genesis is without question supporting Pro-Life. The only way to resolve the 3 math enigmas is to think that both Fatherhood and Childhood (i.e. human "life) start at conception. Without thinking that way the math won't be solved. I believe readers misinterpreted when "life" began prior to about 1970 AD. They thought it started at birth. Then we obtained acceptable scientific proof that it begins at conception. Thus, these enigmas have existed since the Hebrew Bible but couldn't be solved until recent years. Commented Apr 25, 2023 at 19:45

James Jordan (who has done a lot of work on biblical chronology) asserts that the reasons are to reinforce the flood process as a new creation. He writes:

As regards the Flood year itself, it began in the second month, which would be in the spring. We can make a good guess as to the various days of the year by taking note of the number of seven-day sequences that show up in connection with it. This indicates a sabbath pattern. We start off with the assumption, grounded in Biblical theology, that God’s announcement of the Flood came on a sabbath, the day of judgment. This was am 1656, month 2, day 10 (hereafter 2/10/1656), according to Genesis 7:1-4.

The actual judgment commenced on the following sabbath, 2/17/1656 (Gen. 7:10-11). After 40 days the rain stopped (Gen. 7:12, 17). If we assume a 30-day second month, we come to 3/27/1656, a Thursday. On Thursday, the fourth day, the fishes and birds were made. On this Thursday of the Flood year, only fishes and birds (surviving by lighting on floating debris) would exist on the earth. The only animals and men were in the Ark.

The waters receded and after 150 days the Ark rested (invisibly) on Mount Ararat, on 7/17/1656, which is a Tuesday, the day the dry land began to appear in Genesis 1.

The tops of the mountains became visible on 10/1/1656 (Gen. 8:5). Let us provisionally assume this to be a Tuesday, corresponding to the third day of creation week, when the dry land appeared. This would mean that if the tenth month was 29 days, the raven and dove sent out 40 days later (11/11/1656) were sent out on a sabbath (Gen. 8:6-12). The doves sent out seven and fourteen days later were also sent out on sabbaths (11/18/1656; 11/25/1656).

Following from this, if the eleventh month was 29 days and the twelfth was 30 days, or vice versa, then the drying of the surface of the earth and uncovering of the Ark on 1/1/1657 (Gen. 8:13) was on a Sunday, the first day of a new creation. Similarly, if the first month of 1657 was 30 days, then the emergence from the Ark on 2/27/1657 (Gen. 8:14) was also a Sunday, the eighth Sunday of the year.

We provisionally assumed above that 10/1/1656 was a Tuesday, and this is the case if we assume 29-day months for the seventh, eighth, and ninth months.

Now let us cross-check the scheme. We found reason to believe that months 2,3,4,5,6,11/12 were 30 days, and that 7,8,9,10,11/12 were 29-days, with the first month of 1657 a 30-day month. This gives us a roughly 50-50 spread, which is what is required for lunar months.

  • @GoneQuiet I think he would be referring to the Creation week, where the "evening and morning" of Day 6/Day 7 was the judgment of Adam's sin, meaning he could not enter into God's rest. Jordan also sees the "Lord's day" in Rev. 1 as both the day of worship and a day of judgment, when Jesus comes to assess the churches, to discipline and encourage.
    – Mike Bull
    Commented Apr 22, 2013 at 1:00
  • Any chance you can summarize this or add some analysis of it. Stack Exchange answers really should not just be quotes of other authors as that defeats the mission of providing freely shareable material - a quoet only answer retains the copyright of the original author.
    – ThaddeusB
    Commented Oct 12, 2015 at 2:57

This answer has two parts.

Part I, to why there are so many dates in the Flood narrative

According to the Documentary Hypothesis, the canonical Flood narrative comes from the combination of two narratives, an older non-P and a newer P [1] [2]. The non-P text had incremental dates while the P text had absolute dates, which P tried to match to the non-P incremental dates.

Part II, to why the dates in the Flood narrative are the specific ones they are

For some dates the answer is quite simple, and I will give them next.

Noah.600.2.17, when the Flood starts (reworked from [2]): Original non-P began with the building of the ark over 40 days (now omitted) followed by 7 days of waiting inside the ark: 40 + 7 = 47 days. P added these 47 days to the start of the year of the Flood, Noah.600.1.1, resulting in an absolute start date: Noah.600.2.17 (Gen 7:11).

Noah.600.7.17, when the ark rests on Mount Ararat: The waters prevailed upon the earth during an interval of 150 days (Gen 7:24), towards the end of which they started to recede, so that at the end of that 150-day interval (Gen 8:3), i.e. on Noah.600.7.17 if and only if all months from 2 to 6 have 30 days, the ark rested upon the mountains of Ararat (Gen 8:4).

For the date Noah.601.2.27 of the day when the earth was dry, as well as for the 150 days since Noah.600.2.17 to Noah.600.7.17, the answer is that, in the Genesis text due to the Priestly source, the Flood chronology and the division of Noah's lifespan by the Flood were designed to reflect the replacement of an old 360/390-day month-based calendar by a new 364/371-day week-based calendar associated with the enactment of the weekly Sabbath. This sabbatical calendar was not identical to that in 1 Enoch, Jubilees and Qumran, as its year began on Sunday. In the Flood narrative, the old calendar was in effect up to, and including, the year of the Flood (1656 AM & Noah's 600th year), and the enactment of the new calendar at the beginning of Noah's 601st year required a 10-day date advance, just as the enactment of the Gregorian calendar did in 1582 [3]. Noah's 600 years of life up to, and including, the year of the Flood are twice the old calendar's 300-year intercalation cycle while Noah's 350 subsequent years are twice the new calendar's 175-year intercalation cycle, which is also the same as Abraham's lifespan.

Calling A the old calendar and C the sabbatical calendar, since A.days(1..1656) = 604845 while C.days(1..1656) = 604835, the enactment of the sabbatical calendar required a date advancement of 10 days. This was achieved by making the last day when calendar A was in effect, A.1657.1.1 = A.Noah.601.1.1 (which was at the same time C.1657.1.11 = C.Noah.601.1.11) to be succeded by C.1657.1.12 = C.Noah.601.1.12.

Therefore the day when the earth was dry, C.Noah.601.2.27 in the new calendar, would have been A.Noah.601.2.17 in the old calendar, the same date as that of the beginning of the Flood. Thus, since 1656 was a leap year in the old calendar, the time elapsed since the beginning of the Flood till the earth was dry was 390 days.

This allows for a simple explanation of the date identity of these two events in the LXX: whereas the editor of the LXX vorlage was aware of the notion that both events occurred on the same calendar date in the same calendar, either he was not aware of the notion that a new calendar was enacted at the beginning of Noah.601 with a 10-day date adjustment or he rejected that notion altogether, since anyway the date adjustment required by his longer time since Creation to Flood would have been larger. Therefore he just changed the first date to be the same as the second. Similar considerations apply to the book of Jubilees and to 4Q252, whose authors, already fully unaware of the notion of calendar replacement, instead changed the second date to be the same as the first.


[1] Project TABS (Torah and Biblical Scholarship) Editors, "A Textual Study of Noah's Flood", online at https://www.thetorah.com/article/a-textual-study-of-noahs-flood

[2] Davidson, P. (2017), "Reading the Fractures of Genesis: Noah’s Flood", online at https://isthatinthebible.wordpress.com/2016/11/06/reading-the-fractures-of-genesis-noahs-flood/

[3] Argentus, Johannes (2020), "The Priestly Flood chronology: a case of calendar replacement with Gregorian-like date adjustment", online at https://www.academia.edu/43988569/The_Priestly_Flood_chronology_a_case_of_calendar_replacement_with_Gregorian_like_date_adjustment


"Teach us to count our days rightly, that we may obtain a wise heart."

  • Psalm 90:12

Righteousness begins with measuring and acknowledging time. Sacrificial offerings are done on the start of the month (Numbers 28:11) and at the due time (Numbers 28:1-2).

The repetition of dates in Noah's flood story could be saying that we need to make better productive use of our time. Most of humanity experienced the "end" during the flood. So it makes sense to be more reflective of time.

Some bad people only live for the moment and don't plan for the future.

This becomes true of the post-flood situation - because lifespans decrease significantly and fertility does expire when you get older. Most of Shem's genealogy in Genesis 11 involves people having children in their 30's. Compare this to Genesis 5 when a lot of people can have a child at past the age of 70 and well into 187 (Genesis 5:25).

Cain does not respect time. "In the course of time, Cain brought an offering to YHWH..." - Genesis 3:3. Cain perhaps was not acknowledging time properly. Cain's lineage contains no record of years (Genesis 3:17-24), probably because Cain and his descendants see time as something that's against them, something that defines their mortality. Time is associated with struggle (Genesis 3:17) and Seth's genealogy acknowledges years - they respect mortality.


Not the answer you're looking for? Browse other questions tagged or ask your own question.