Origin of the "½ age + 7 years" rule of age difference for dating [edited title]

How big can difference in age be for dating? ½ age + 7 years.
Example: A 80 year old women may date a man of anywhere from 47 years to 146 years old.
Anyone know where the ½ + 7 formula originated?

From what I’ve read in historical fiction it seems as if it was once more socially acceptable to date/marry younger women then you can in 21st Century America. Is this true? If so, why?

I call the “1/2 your age + 7” rule the “socially correct rule”, or something like that. Meaning that it’s the youngest a MAN can go without people wondering about him (I know there are lots of exceptions!!)

it isn’t applicable at the extremes of age (like your 80-year old example) but seems to fit pretty well from 20-50 or so. Examples: If a guy is 30, he could date a 22-year-old without too many odd looks. But an 18-or 19-year od would probably get him some looks. If he’s 40, then the “minimum” age would be 27 before people starting thinking things of him.

But of course it breaks down, like any approximation. So a 10-year old man can only date women 12 or older? Yeah, it gets silly. A 80-year old man and a 47 -year old woman would definitely raise some questions too.

I say it only applies to men because it is generally more socially common for men to date somewhat younger women (as in the above examples) but not the other way around. Heck, I’m dating a girl 9 weeks older than me and a friend of mine said that would bother him! 9 weeks!! Give me a break.

Though there are all kinds of exceptions and contrary examples, I know I know. Hey, I didn’t make up this “rule”!!

Odd that I’d never heard of this rule before, but maybe there’s something too it.

When I was 28 I got quite involved with a 20 year old and right at the beginning something gnawed at me though I could never put my finger what it was. Seeing as she violated the rule by a year, maybe that was it. But it never bothered her (or her parents).

Alas, it was a long time ago, she was the one that “got away”.

Tross, I haved edited your thread title to make it clear you want factual answers about the origin of the rule rather than opinions on its appropriateness. Anyone wishing to start a poll on the appropriateness may of course start a thread in the IMHO forum.

moderator GQ

I THINK that it’s some sort of Muslim guideline. I remember reading about it in connection to some Muslim cultural thingy or other. However, I have no cites.

Me things I thinks what you thinks Lynn.

I recall it is a Muslim concept yet I remember no cites.

Hopefully some here ill know the exact source.

I remember reading this in ‘Poor Richard’s Almanac’ or another of Ben Franklin’s writings. Something that the perfect age for a wife (as opposed to dating) is half the husbands age plus seven years.

Doesn’t mean ol’ Ben didn’t steal it from elsewhere, though.

I first heard of this rule on the SDMB. :slight_smile:

It seems to be a good rule of thumb for helping to point out which people, in a culture whose surface layer is constantly changing, might have the most similar cultural baggage, and thus be most compatible. Of course, actual experience trumps such rules every time.

I always thought that it was a recent rule, originating here in the English-speaking world during times of progress or change, so at least after the Age of Discovery; that it might be considerably older surprises me.


“pi” age plus seven years? You mean multiply my age by pi and then add seven?

So I can date a woman as long as she’s younger than 145?

And, reversing the direction, I’m fair game for any woman older than 11 3/4?

“useful” !!

Check your character mapping AHunter3. That’s one half plus seven years.

It should be 0.5 age + 7 years. The character mappings don’t, well, map between OSes.

I suggest using the web page I built just for this purpose:


I thought it appeared in Little Women, but I don’t remember for sure.

So, a 21 year old can date a 14 year old. Nice. :dubious:
I believe the .5A + 7 rule works better and prevents charges of statutory rape. Which is where this latter rule probably derived from, since it makes an adult of 18 only date those who’ve reached a common age of consent (16) or older.


What about the proper range for IQ differences?

*Originally posted by bibliophage *
**Tross, I haved edited your thread title to make it clear you want factual answers about the origin of the rule rather than opinions on its appropriateness. Anyone wishing to start a poll on the appropriateness may of course start a thread in the IMHO forum.

Thank you. I’ll get my titles right in the future. Sorry for your trouble.

Some links:

Question at World Wide Singles

.5A +7 Calculator at Turn Me Loose


0.5 * age + 7, then? ::does figures:: That would be 29.

Is that the minimum, I assume? And to get maximum you subtract 7 years and double? That’s 74.

Hmm, more reasonable.

I’m shocked to discover that when I turn 42 later this month, it’ll be socially acceptable for a 70 year old women to date me.

That’s funny. I remember hearing this calculation as representing the average age of a man’s second wife. I guess someone dreamed up that version to explain the ‘trophy wife’ phenomenon among some groups.