# Birthday age question... **URL:** \ **Category:** Factual Questions\ **Created:** [April 26, 2012, 3:25pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027 "2012-04-26T15:25:05Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![bmasters1](https://avatars.discourse-cdn.com/v4/letter/b/b5e925/32.png) [@bmasters1](https://boards.straightdope.com/u/bmasters1)\ **Post date:** [April 26, 2012, 3:25pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/1 "2012-04-26T15:25:05Z")
Why is it, according to the rules of birthdays, that in order to get another figure added onto your age, you must reach your DOB in the following calendar year? By this I mean, that Rod Roddy, IIRC, was born in Sep. 1937, and died in Oct. 2003. Since Rod passed his DOB prior to his death, the difference between 1937 and 2003 (66) applies. OTOH, Dick Clark was born 11/30/29, and passed 4/18/12. If he had reached that DOB of 11/30/29 this year, he would have been 83. He fell short however, and so his age was only 82. What I’d like to know is why birthdays are set up like this. ---
**Author:** ![Munch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/munch/32/5281_2.png) [@Munch](https://boards.straightdope.com/u/Munch)\ **Post date:** [April 26, 2012, 3:26pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/2 "2012-04-26T15:26:36Z")
Uh… Because your age is the number of years you have successfully completed. Full stop. ---
**Author:** ![manila](https://avatars.discourse-cdn.com/v4/letter/m/e5b9ba/32.png) [@manila](https://boards.straightdope.com/u/manila)\ **Post date:** [April 26, 2012, 3:34pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/3 "2012-04-26T15:34:22Z")
I _believe_ Korean’s count age as being born at 1 and 12 months later you are 2. Perhaps one of our Korean dopers can shed more light on this? ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [April 26, 2012, 3:43pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/4 "2012-04-26T15:43:31Z")
> [@bmasters1](#): > > What I’d like to know is why birthdays are set up like this. It’s just by convention. Little kids always like to get all the credit as they can (“I’m four and a half”) but adults just round down. I suppose you could say, “Dick Clark was 82.382 years old.” I have a Chinese friend who told me that Chinese use the same convention as described above for Koreans. (They round up.) ---
**Author:** ![Kimmy\_Gibbler](https://avatars.discourse-cdn.com/v4/letter/k/bbe5ce/32.png) [@Kimmy\_Gibbler](https://boards.straightdope.com/u/Kimmy_Gibbler)\ **Post date:** [April 26, 2012, 3:44pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/5 "2012-04-26T15:44:20Z")
> [@bmasters1](#): > > Why is it, according to the rules of birthdays, that in order to get another figure added onto your age, you must reach your DOB in the following calendar year? Fun fact: At common law and for the SSA, you attain the next year of age on the day immediately before your birthday. [SSR 63-15](http://www.socialsecurity.gov/OP_Home/rulings/oasi/09/SSR63-15-oasi-09.html). ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [April 26, 2012, 3:50pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/6 "2012-04-26T15:50:23Z")
> [@manila](#): > > I _believe_ Korean’s count age as being born at 1 and 12 months later you are 2. This is common in a lot of Asian cultures, including Indian. It’s called counting age in _current_ years, rather than in _elapsed_ years as in the typical Western system. Note that we typically count **calendar** years as current (e.g., this year is called “2012” even though the Common Era is only 2011 years and nearly four months old, but it’s the two thousand and twelfth year of the era so that’s what we call it), but the **ages** of individuals in elapsed years. I believe the OP is asking why we don’t just round up our age values to the **nearest** integer elapsed year—so, for example, six months after your 50th birthday you start calling yourself 51. And I think the only real reason is the PITA factor. Easier and simpler just to use your original birthdate as the conventional calendar date when the age-o-meter rolls over. ---
**Author:** ![whitetho](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whitetho/32/1059_2.png) [@whitetho](https://boards.straightdope.com/u/whitetho)\ **Post date:** [April 26, 2012, 4:02pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/7 "2012-04-26T16:02:02Z")
> [@bmasters1](#): > > OTOH, Dick Clark was born 11/30/29, and passed 4/18/12. If he had reached that DOB of 11/30/29 this year, he would have been 83. To add to what **Kimmy\_Gibbler** said, it is my understanding in the United States, following English Common law, Clark would have turned 83 as of 12:00:01 AM on 11/29/2012, i.e. just past midnight on the day before his birthday. (Someone correct me if I am wrong. Also, how does Louisiana, which doesn’t follow common law, handle this?) ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [April 26, 2012, 4:47pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/8 "2012-04-26T16:47:00Z")
The same reason 2001-2100 is the 21st century? ---
**Author:** ![J\_Cubed](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@J\_Cubed](https://boards.straightdope.com/u/J_Cubed)\ **Post date:** [April 26, 2012, 5:11pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/9 "2012-04-26T17:11:00Z")
> [@whitetho](#): > > To add to what **Kimmy\_Gibbler** said, it is my understanding in the United States, following English Common law, Clark would have turned 83 as of 12:00:01 AM on 11/29/2012, i.e. just past midnight on the day before his birthday. (Someone correct me if I am wrong. Also, how does Louisiana, which doesn’t follow common law, handle this?) I have never ever heard of this concept, and it sounds strange. That obviously doesn’t mean it’s wrong, and **KG** linked to a reference, but what is the reasoning here? Did some ancient English royal census-taker just have a screw loose, or does it prevent some temporal paradox or something? ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [April 26, 2012, 5:44pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/10 "2012-04-26T17:44:55Z")
> [@J\_Cubed](#): > > I have never ever heard of this concept, and it sounds strange. That obviously doesn’t mean it’s wrong, and **KG** linked to a reference, but what is the reasoning here? Did some ancient English royal census-taker just have a screw loose, or does it prevent some temporal paradox or something? Well, unless you want to go down to the hours and minutes, then you’d complete a whole year once you hit the day before your birthday. If you’re born June 4th, then on June 3rd, you’ve been alive for each calendar day of the year. “Was he alive June 1st? Yes. June 2nd? Yes. June 3rd? Yes, today. June 4th? Yes, last year.” And so on. So the day you’re 365 days old is the day before your birthday. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [April 26, 2012, 6:19pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/11 "2012-04-26T18:19:45Z")
Ignoring the sidetrack onto weird rules about getting a year older the say before your birthday (which I’d never heard of) I’m rather puzzled by the OP’s question. I don’t see how it could be any other way, unless you arbitrarily chose January 1 as the marker for becoming a year older. But that would lead to the absurd situation of babies born shortly before midnight on December 31 having their “first birthday” almost immediately. The whole point of a birthday is that it’s the anniversary of your birth. My daughter was born on August 17 last year, so she’s not one year old yet - she’s only a little over eight months. **Chessic Sense** , I don’t follow your logic. Even if you count down to the hours and minutes, you’re still not a whole year old until the day of your birthday. My daughter was born at 8.30pm. I’d say she wasn’t “one day old” until August 18 - and then not till the evening if we’re being picky. She won’t be one year old until August 17 this year, at 8.30pm (though once we’re talking whole years it seems pretty pointless quibbling down to the time of day). ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [April 26, 2012, 6:34pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/12 "2012-04-26T18:34:58Z")
> [@Colophon](#): > > **Chessic Sense** , I don’t follow your logic. Even if you count down to the hours and minutes, you’re still not a whole year old until the day of your birthday. My daughter was born at 8.30pm. I’d say she wasn’t “one day old” until August 18 - and then not till the evening if we’re being picky. She won’t be one year old until August 17 this year, at 8.30pm (though once we’re talking whole years it seems pretty pointless quibbling down to the time of day). I think he’s pointing out that you could be alive during 365 days (or 366 in a leap year), without being alive for the full year. So you could be born just before midnight on Jan. 1, and on Dec. 31 just after midnight you’ve been alive during 365 (or 366) days. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [April 26, 2012, 6:44pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/13 "2012-04-26T18:44:55Z")
> [@TriPolar](#): > > I think he’s pointing out that you could be alive during 365 days (or 366 in a leap year), without being alive for the full year. So you could be born just before midnight on Jan. 1, and on Dec. 31 just after midnight you’ve been alive during 365 (or 366) days. But being alive on _X_ days isn’t the same as being _X_ days old. Just the same as being alive in _Y_ years isn’t the same as being _Y_ years old. Take my daughter. (Please - we need the sleep 😃 ) She came into the world in 2011, and it’s now 2012. Is she two years old? No, she’s eight months old. Similarly, I was born in 1977. That means I’ve been alive in 36 calendar years, including this one. But I’m only 35 - and I’ve already had my birthday this year. By the same token, I am now in my fifth decade - 1970s, 1980s, 1990s, 2000s, 2010s - but I’m not 50 years old. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [April 26, 2012, 6:45pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/14 "2012-04-26T18:45:23Z")
Early 18th century Norwegian censuses record age similar to the Korean method. The heading for the 1865 form says something like “Age, the current age year included” (Yeah, it’s odd in Norwegian as well.) The 1801 instructions have “The current, and not the achieved year of age should be recorded”. The Norse sagas generally give age in winters. We celebrate birthdays and give age in completed years because that’s the convention. It’s probably become the convention because it’s what makes the most sense mathematically. ---
**Author:** ![Wheelz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wheelz/32/5718_2.png) [@Wheelz](https://boards.straightdope.com/u/Wheelz)\ **Post date:** [April 26, 2012, 6:48pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/15 "2012-04-26T18:48:51Z")
One year after you’re born, you’re one year old. One year after that you’re two years old. In between, you’re every fraction between the two integers, of course. But it’s just easier to count things in whole numbers, including years, so that’s what we do. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [April 26, 2012, 7:05pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/16 "2012-04-26T19:05:20Z")
it is common to just know the year of a nonrelated person’s birth. their age to you would be as if they were born on January 1st. once into adulthood this doesn’t seem to be of serious consequence looking at the age of others for casual purposes. ---
**Author:** ![Kimmy\_Gibbler](https://avatars.discourse-cdn.com/v4/letter/k/bbe5ce/32.png) [@Kimmy\_Gibbler](https://boards.straightdope.com/u/Kimmy_Gibbler)\ **Post date:** [April 26, 2012, 7:30pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/17 "2012-04-26T19:30:31Z")
So, I consulted the sources cited in the SSR and went down the rabbit hole of “Why do you advance in age on the day before your birthday?” [QUOTE=United States v. Wright, 197 F. 297 (8th Cir. 1912)] The law ordinarily taking no cognizance of fractions of days, one becomes of full age the first moment of the day before his twenty-first anniversary. [/QUOTE] [QUOTE=State v. Clarke, 3 Del. (3 Harr.) 557, 18 WL 3673 (1840)] To ascertain when a man is legally “of the age of twenty-one years,” we must have reference to the common law, and those legal decisions which from time immemorial have settled this matter, in reference to all the important affairs of life. When can a person make a valid will; when can he execute a deed for land; when make any contract or do any act which a _man_ may do, and an _infant_, that is, a person under the age of twenty-one years, cannot do? On this question the law is well settled; it admits of no doubt. A person is “of the age of twenty-one years” the day _before_ the twenty-first anniversary of his birth day. It is not necessary that he shall have entered upon his birth day, or he would be more than twenty-one years old. He is, therefore, of age the day before the anniversary of his birth; and, as the law takes no notice of fractions of a day, he is necessarily of age the whole of the day before his twenty-first birth day; and upon any and every moment of that day may do any act which any man may lawfully do. (1 _Chit. Gen. Prac._ 766.) “It is to be observed, that a person becomes of age on the first instant of the last day of the twenty-first year _next before_ the anniversary of his birth; thus, if a person were born at any hour of the 1st of January, A. D., 1801, (even a few minutes before 12 o’clock of the night of that day,) he would be of full age at the first instant of the 31st of December, A. D. 1821, although nearly forty-eight hours before he had actually attained the full age of twenty one, according to years, days, hours and minutes; because there is not in law in this respect any fraction of a day; and it is the same whether a thing is done, upon one moment of the day or another.” [/QUOTE] [QUOTE=Wells v. Wells, 6 Ind. 447, 1855 WL 3723 (1855)] If from this statement we fix his birth-day at September 23, 1828, he was of age [twenty-one years as of] September 22, 1849. [/QUOTE] [QUOTE=Hamlin v. Stevenson, 34 Ky. (4 Dana) 597, 1836 WL 2122 (1836)] A person is of full age on the day preceding the 21st anniversary of his birth. [/QUOTE] Neither _Wells v. Wells_ nor _Hamlin v. Stevenson_ cite any authority or furnish any rationale for the holding. The authority cited in _State v. Clarke_ does note that this rule might allow someone to attain age 21 up to nearly forty-eight hours before the actual elapse of twenty-one full years from the instant of his birth. But adhering to the premise that the law treats fractions of days as immaterial, “it is the same whether a thing is done, upon one moment of the day or another.” This doesn’t really answer why an age is attained on the day before one’s birthday, but it does sound appropriately sententious for a nineteenth century court. The SSR also cites another case _Frost v. State_, 45 So. 203 (Ala. 1907), which was **overruled** by the same Supreme Court of Alabama eight years later in _Graves v. Eubank_, 87 So. 587 (Ala. 1921): > [@](#): > > . . . [A] majority in each instance were of the opinion that Frost did not become 45 years of age prior to the time the tax became due, October 1, 1906. He was born October 2, 1861, and by excluding his birthday, which was conceded to be proper in the opinion as well as the briefs in said case, he did not become 45 years old before the tax became due, October 1st, but on the day that it became due. In other words, he was 45 years of age the day the tax was due, and going upon the theory that but one day could be excluded, he was not 45 before the tax became due and was not therefore exempt from the payment of same; and there was some reason for feeling that the right result had been reached in said case, notwithstanding the unsoundness of the reason given for same. Upon a reconsideration of this Frost Case, however, we are not only of the opinion that the reasoning of same was properly overturned in the two later cases, but it should have been expressly overruled. Under the law as applicable, Frost was 45 years of age October 1, 1906, the day the tax fell due, and if the Constitution exempted those over 45, he would have been liable; but upon a closer analysis of section 194 of the Constitution, we are of the opinion that it is the fixation of a tax on certain ones and not an exemption. In other words, it places a tax on those “over age of 21 years and under 45 years of age.” Frost on October 1, 1906, was 45 years of age and not “under the age of 45” as fixed by the Constitution. We therefore expressly overrule said case of _Frost v. State_, 153 Ala. 654, 45 South. 203. Honestly, I not sure what the hell is going on in this, except it does seem that they did _not_ overrule the day-before-your-birthday aspect of the case. But holy shit, this is a lot of litigation on what seems to be a not very complicated question. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [April 26, 2012, 7:35pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/18 "2012-04-26T19:35:04Z")
Traditionally, in Korean culture and I suspect in a lot of East Asian cultures, you are age 1 the day you are born. You advance your age by one each new year (the lunar one, not January 1). So, a baby born on New Year’s Eve would be 2 on their second day of life. These days, younger Koreans count their birthdays (on the western calendar). So, they’re age 1 on the day they’re born, and turn 2 on their next birthday. While some amusing arguments can occur (and I’ve been in them 😃 ), they come down to how one answers “how old are you?”. Americans answer with how many whole years have past since they were born. Koreans either answer with how many birthdays they’ve had (counting the day they were born as their first birthday) or answer with how many (lunar calendar) years they’ve been alive in. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 26, 2012, 7:45pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/19 "2012-04-26T19:45:57Z")
> [@](#): > > But being alive on X days isn’t the same as being X days old. Just the same as being alive in Y years isn’t the same as being Y years old. For that matter, there have been a handful of people who’ve been alive in three centuries. Would you say that they were three centuries old? ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [April 26, 2012, 7:56pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/20 "2012-04-26T19:56:55Z")
> [@Colophon](#): > > I don’t see how it could be any other way, unless you arbitrarily chose January 1 as the marker for becoming a year older. But that would lead to the absurd situation of babies born shortly before midnight on December 31 having their “first birthday” almost immediately. There’s an old-fashioned way of counting years in Spanish, counting “springs”, which is sort of similar to that, but if you were born in Spring you counted as “having 1 spring” the next year (in Spanish we “aren’t X years old”, we “have X years”). Since winter is the period that sees most deaths (even nowadays), reaching Springtime meant you’d survived another year. I’d translate the way those Asian cultures count as “being in their Xth year”; I’d like to know whether that’s literally how they put it. [Next page](https://boards.straightdope.com/t/birthday-age-question/620027.md?page=2)