Birthday age question...

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.


Because your age is the number of years you have successfully completed. Full stop.

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?

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.)

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.

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.

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?)

The same reason 2001-2100 is the 21st century?

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.

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).

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 :smiley: ) 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.

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.

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.

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.

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?”

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):

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.

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 :smiley: ), 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.

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?

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.