# Age difference in relationships: rule of thumb? **URL:** \ **Category:** Factual Questions\ **Created:** [June 30, 2005, 2:38pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515 "2005-06-30T14:38:35Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![brianmelendez](https://avatars.discourse-cdn.com/v4/letter/b/65b543/32.png) [@brianmelendez](https://boards.straightdope.com/u/brianmelendez)\ **Post date:** [June 30, 2005, 2:38pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/1 "2005-06-30T14:38:35Z")
I have occasionally heard a rule of thumb about age differences in relationships: that a man shouldn’t date a woman who isn’t at least seven years older than half his age. I just mentioned this “rule” to a friend who had never heard it, and she wondered where it came from. I have heard it more than once (and vaguely remember some source, not necessarily a credible one as I recall, attributing it to Gandhi), but I don’t really know where it came from. Does anyone here know? I also thought that I saw a thread on this topic about a year ago, but couldn’t find it when I searched. Thanks! ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [June 30, 2005, 2:45pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/2 "2005-06-30T14:45:18Z")
Lemme see, my last girlfriend was 43, I’m 25 so I had that one covered. ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [June 30, 2005, 2:55pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/3 "2005-06-30T14:55:58Z")
In _Malcom X_ Elijah Muhammed says pretty much that rule though I can’t remember if it was half plus seven or half plus nine. I don’t know where he got it from. ---
**Author:** ![Jake4](https://avatars.discourse-cdn.com/v4/letter/j/bc8723/32.png) [@Jake4](https://boards.straightdope.com/u/Jake4)\ **Post date:** [June 30, 2005, 3:41pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/4 "2005-06-30T15:41:10Z")
I too have heard the “0.5x + 7” rule. I’ve also heard of “2x - 7” for the upper age limit. I have no idea where they came from. For a 16 year old, the lower limit is 15, upper is 25. For a 18 year old, the lower limit is 16, upper is 29. 21: 17.5, 35. 25: 19.5, 43. 30: 22, 53. 35: 24.5, 63. 40: 27, 73. The problem with this is that you get different ranges of age depending on which person you’re considering. For instance, according to the above, a 21-yr-old could date a 35-yr-old, but the 35-yr-old shouldn’t date below 24.5. Perhaps this is why the upper age limit isn’t referred to as often. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [June 30, 2005, 3:48pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/5 "2005-06-30T15:48:05Z")
I’ve never heard of an explicit formula for the upper bound, but if you phrase the rule properly you don’t need one. Just say that in any relationship, the age of the younger person should be at least half the older person’s age plus seven years. This implies that the age of the older person should be at most twice the younger person’s age minus 14 years, and there’s no inconsistency based on which version of the rule you pick. ---
**Author:** ![elfbabe](https://avatars.discourse-cdn.com/v4/letter/e/b782af/32.png) [@elfbabe](https://boards.straightdope.com/u/elfbabe)\ **Post date:** [June 30, 2005, 3:52pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/6 "2005-06-30T15:52:16Z")
> [@Jake4](#): > > I too have heard the “0.5x + 7” rule. I’ve also heard of “2x - 7” for the upper age limit. > … > The problem with this is that you get different ranges of age depending on which person you’re considering. **Jake4** , either your memory or your algebra is off, that second formula should be 2x - 14. Or really, 2y - 14, if x is the age of the older person and y is the age of the younger person… presuming you want to just switch the formula around and not make up a whole new formula. Demonstration, because math is fun: **x** /2 + 7 = **y** **x** /2 = **y** - 7 **x** = 2( **y** - 7) **x** = 2 **y** - 14 ---
**Author:** ![SnakesCatLady](https://avatars.discourse-cdn.com/v4/letter/s/4af34b/32.png) [@SnakesCatLady](https://boards.straightdope.com/u/SnakesCatLady)\ **Post date:** [June 30, 2005, 3:52pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/7 "2005-06-30T15:52:37Z")
I believe I read the “half plus seven” rule in “Little Women”. ---
**Author:** ![Ike\_Witt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ike_witt/32/283_2.png) [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)\ **Post date:** [June 30, 2005, 3:53pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/8 "2005-06-30T15:53:30Z")
Is there an actual purpose for a rule like this? ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [June 30, 2005, 3:57pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/9 "2005-06-30T15:57:03Z")
> [@adam yax](#): > > Is there an actual purpose for a rule like this? It makes sense for teenagers. ---
**Author:** ![Arwin](https://avatars.discourse-cdn.com/v4/letter/a/51bf81/32.png) [@Arwin](https://boards.straightdope.com/u/Arwin)\ **Post date:** [June 30, 2005, 4:00pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/10 "2005-06-30T16:00:45Z")
I prefer 1x +7 … 😃 And by the way, the only relevant rule that you should be worrying about is the legal one for your country. For the rest, whatever you’re comfortable with. ---
**Author:** ![Maastricht](https://avatars.discourse-cdn.com/v4/letter/m/a88e57/32.png) [@Maastricht](https://boards.straightdope.com/u/Maastricht)\ **Post date:** [June 30, 2005, 4:12pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/11 "2005-06-30T16:12:40Z")
I’ve read about the “half plus seven rule”, not as advice, but as the male ideal. Ideally, a guy wants to date a woman half his age + 7. I’ve done [some googling](http://www.lura.net/03/romance/) > [@](#): > > This rule has been variously attributed to the French, and Muslims, and Jewish matchmakers; but who cares about it’s origins, it works. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [June 30, 2005, 4:52pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/12 "2005-06-30T16:52:03Z")
> [@Maastricht](#): > > I’ve read about the “half plus seven rule”, not as advice, but as the male ideal. Ideally, a guy wants to date a woman half his age + 7. Me, too-- more of a “we wish” than “we should”. As I get older, though, I tend to drop the “+7” part. 🙂 ---
**Author:** ![irishgirl](https://avatars.discourse-cdn.com/v4/letter/i/8edcca/32.png) [@irishgirl](https://boards.straightdope.com/u/irishgirl)\ **Post date:** [June 30, 2005, 9:57pm UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/13 "2005-06-30T21:57:10Z")
It was the standard advice in Etiquette text books back in the day. My parents have a “Lady’s Home Companion” from 1908, as well as a 1940s book on Marriage Etiquette with it. It’s based on the premise that women over 30 are almost unmarriagable, except as the second wives of elderly widowers. In those days marriage was about procreation, and a virgin, fertile, healthy unmarried woman over 30 would be very unusual. ---
**Author:** ![Runs\_With\_Scissors](https://avatars.discourse-cdn.com/v4/letter/r/278dde/32.png) [@Runs\_With\_Scissors](https://boards.straightdope.com/u/Runs_With_Scissors)\ **Post date:** [July 1, 2005, 1:18am UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/14 "2005-07-01T01:18:42Z")
> [@Arwin](#): > > I prefer 1x +7 … 😃 > > And by the way, the only relevant rule that you should be worrying about is the legal one for your country. For the rest, whatever you’re comfortable with. Exactly. It’s nobody’s business what two people of consenting age do. ---
**Author:** ![chaoticbear](https://avatars.discourse-cdn.com/v4/letter/c/f07891/32.png) [@chaoticbear](https://boards.straightdope.com/u/chaoticbear)\ **Post date:** [July 1, 2005, 3:57am UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/15 "2005-07-01T03:57:56Z")
Thank goodness this (apparently) doesn’t apply to men. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [July 1, 2005, 4:17am UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/16 "2005-07-01T04:17:50Z")
No younger than the Scotch you drink. ---
**Author:** ![Bernard\_Marx](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@Bernard\_Marx](https://boards.straightdope.com/u/Bernard_Marx)\ **Post date:** [July 1, 2005, 10:34am UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/17 "2005-07-01T10:34:01Z")
Not a “rule” as such, more of a guideline, but where I work sleeping with a woman one year older than twice your age is known as “getting your boiler’s ticket” ---
**Author:** ![xash](https://avatars.discourse-cdn.com/v4/letter/x/c6cbf5/32.png) [@xash](https://boards.straightdope.com/u/xash)\ **Post date:** [July 2, 2005, 4:21am UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/18 "2005-07-02T04:21:46Z")
Moved to IMHO. - **xash** General Questions Moderator ---
**Author:** ![John\_Carter\_of\_Mars](https://avatars.discourse-cdn.com/v4/letter/j/2bfe46/32.png) [@John\_Carter\_of\_Mars](https://boards.straightdope.com/u/John_Carter_of_Mars)\ **Post date:** [July 2, 2005, 5:09am UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/19 "2005-07-02T05:09:18Z")
> [@brianmelendez](#): > > I also thought that I saw a thread on this topic about a year ago, but couldn’t find it when I searched. I’m too lazy to search, but IIRC, the thread was in IMHO, the title was something like: “May-December romances?” and the OP was **lezlers**. She was thinking about getting into a relationship with a much older man. Incidentally, she want ahead with it, and at last report it was working out very well for her. It was a rather long thread with a lot of good comments. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [July 2, 2005, 5:26am UTC](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515/20 "2005-07-02T05:26:13Z")
[Found it](http://boards.straightdope.com/sdmb/showthread.php?t=275740). [Next page](https://boards.straightdope.com/t/age-difference-in-relationships-rule-of-thumb/310515.md?page=2)