Half-your-age-plus-7 rule

The half-your-age-plus-seven rule is a mathematical guide to judge whether the age difference in an intimate relationship is socially acceptable. Mathematically speaking, the rule is (Minimum Age) = (Age of the Older Individual) / 2 + 7.

For example, if Shane is 30 and wants to date Kristen, who is 20, he would be in violation of the rule, since the minimum age being 22. Notice, however, that the age difference matters less as the potential partners grow older. In this case, Shane would have four years to wait before the age difference in the relationship was "socially acceptable".

Note that what is implied by "socially acceptable" is largely a cultural construct, and has varied over time. Anna Nicole Smith and J. Howard Marshall were 26 and 89 at the time of their relationship.