A common rule of thumb, at least on the internet, is that it’s okay to be interested in someone “half your age plus seven” years. According to this rule, it would not be creepy for a 30 year old to date a 22 year-old, but an 18 year-old would be off-limits. Although this is a fun rule of thumb, what does research say about age preferences for potential mates?

There are two things that predict a preferred partner’s age: (a) your age and (b) your biological sex (male vs. female). From an evolutionary perspective, it makes sense for women to prefer mates with resources and to like partners who are more established, both of which are more likely in older partners. Men, in contrast, are hypothesized to be most attracted to women in their reproductive prime, which tends to be when they are younger.

Data from Kenrick and Keefe1 support these predictions. Younger men tend to prefer women a few years younger or older than themselves; but as they get older, they increasingly prefer younger women relative to their own age. The range doesn’t get wider as men get older, but it does get younger. Women’s preferences, on the other hand, hold relatively constant across their lives, not going more than a few years below their own age (extra-credit if you can identify the “cougar zone” in this figure), but women remain keen on men up to 10 years older than themselves.

The findings above represent people’s mate preferences; but what about age differences in actual relationships? After all, you can’t always get what you want. It turns out that, on average, women tend to be married to men a few years older than themselves (2-5 years). However, younger men (i.e., in their 20’s) tend to be married to someone of a similar age, but as they get older their wives get younger. For example, by their 50’s the average male has a wife who is 10 years younger than him.

The “half your age plus seven” rule of thumb probably helps you avoid being a creep, but is it accurate? Much to my surprise, when overlaying a line representing the rule of thumb on Kenrick and Keefe’s1 results (see red line in the figure below), you can see it closely matches the low end of the range (i.e., youngest preferred) for all but the oldest men. However, it doesn’t represent women’s preferences at all. So maybe there is a kernel of truth the rule, at least for men. Using the Mythbusters system, it seems that this one is (partly) confirmed.

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1Kenrick, D. T., & Keefe, R. C. (1992). Age preferences in mates reflect sex differences in human reproductive strategies. Behavioral and Brain Sciences, 15, 75-133.

Dr. Benjamin Le – Science of Relationships articles | Website/CV

Dr. Le’s research focuses on commitment, including the factors associated with commitment and its role in promoting maintenance. He has published on the topics of breakup, geographic separation, infidelity, social networks, cognition, and need fulfillment and emotions in relationships.