"Half your age plus seven" is the rule.
I'm 24.
24 / 2 = 12, + 7 = 19
24 - 7 = 17, x 2 = 34
My "this isn't creepy" age range is therefore 19 to 34.
Just to be safe, I bump the 19 up to 20.
I'm not into older women, so I drop the 34 to 26.
My preferred age range is therefore 20 to 26.