According to internet lore, there's a mathematical equation that governs the lower bound for the socially acceptable age of a potential dating partner: half your age plus 7, or, in mathematical terms, if x is your age then the lower bound is f(x) = x/2 + 7.

Seems simple, right? if you're 20, then the minimum socially acceptable age for a date is 17. But it was The Ragbag who pointed out that this rule has a duality: for the date to be socially acceptable, the rule must be adhered to by your date as well. In other words, there's a socially acceptable **maximum** too, given by inverting the equation:

It was only yesterday that i realised that the rule of thumb for dating people of different ages (the “half your age plus 7” rule) determines not only the lower bounds for dating but the upper bounds as well—that for each ½x + 7, there is a corresponding 2(x-7). For the last 15 years of my life, i have been ignoring an entire market segment, namely those of the genus

cougar.

The Ragbag handily plotted out the socially acceptable upper and lower bounds for dates at various ages in the chart below:

Notably, the chart also implies that there is a socially acceptable lower bound for your *own* age: below the age of 14, by this rule, you shouldn't be dating at all.

Incidentally, if you're wondering how well is this rule adhered to in practice, the dating website okcupid.com has done an extensive analysis of age preferences amongst their members. A really interesting analysis (and quite sophisticated - maybe done in R?), especially for heterosexual males looking for the ideal age-ranges for potential dates.

The Ragbag: The half your age plus 7 rule

I love dating and this is why I always read free dating tips to apply them.....

Posted by: ajay | September 30, 2010 at 22:12

But it was The Ragbag who pointed out that this rule has a duality: for the date to be socially acceptable, the rule must be adhered to by your date as well. In other words, there's a socially acceptable maximum too, given by inverting the equation:

Posted by: Dating Rule Book | October 16, 2010 at 17:32

I agree with you. You have given to us with such an large collection of information. Great work you have done by sharing them to all. simply superb.

Posted by: Filipino Blogger | April 04, 2011 at 07:48

Hey David, I am, to say the least intrigued with your info and would like permission to put your graph on my site and see what kind of response I get. I understand "stats" but I would like non-stat feedback from my Y audience.

Posted by: DJ get your ex back Berry | July 04, 2011 at 11:00

DJ, feel free to reproduce the chart but please link back here as the source.

Posted by: David Smith | July 05, 2011 at 09:31

great tips. i remember these fondly when gas was a dollar a gallon. i think that we probably shouldn’t fall back on these, but i think everyone will adopt a few of them

Posted by: y8 | October 13, 2011 at 13:44

Hi David

I hadn't thought much about this before!

A number of the online dating sites interview women in their 30's who are comfortable with being approached by men who are 15-20 years older than them.

I thought that this was a bit unusual but your chart seems to uphold their observations.

Well done!

Posted by: Get Your Ex Back | November 09, 2011 at 18:53

I'm always sorprise how we can apply mathematics in love. We make all this experiments and theories, are we sure that it can work? We're too much different to know the best positive and perfect love match.

Posted by: Marcella | February 01, 2012 at 04:19

Actually, the original chart (with more detail) as well as the "upper limit" formula comes from here:

http://ianselvarajah.com/2007/03/malefemale-relationship-age-difference.html/

Cheers! :)

Posted by: Ian | February 05, 2013 at 07:24