The rule is well-known and easy to calculate from the mind. But it does have flaws in that awkwardness regard.
Still weirds me out that according to the rule, a 75 year old could date a 45 year old. Maybe the graph should be called “Legally OK, socially questionable” - ie. the grey zone.
A version that could exclude this socially grey zone would be;
(age * 0.75) + 3.25
The .25 is added to make more numbers less strange. Round to nearest full number. If the outcome is higher than the person’s own age, that indicates you’re too young to date. In this case the ‘minimum’ would be 15 for both involved, similar to the original formula.
For 20, it’d be 18.
For 25, it’d be 22.
For 45, it’d be 37.
For 75, it’d be 60.
For 90, it’d be 71.
Inversely, it’d mean that the maximum ages would be calculated as:
(age / 0.75) - 3.25
20 and 23.
25 and 30.
45 and 57.
75 and 97.
90 and 117.
majster@lemmy.zip 22 minutes ago
At 23 she could be 5 years in the workforce. People vary quite a lot.