Apparently the answer is “20k more than the woman you plan to wife up”.
The gap between married women and married men’s average earnings is about 20k regardless of actual earnings until men are in their 30s, when married men’s average goes up into 40k more than the married women average through their 30s.
So guys who are married in their early 20s average 30k, but girls married in their early 20s average 10k. Mid20s, 50k/30k, respectively. Mid30s, 70k/50k.
Another way to look at it is that single men never boost their earnings out of the range they share with married women (for both single men and married women, average income peaks around 50k/yr through 30s and 40s). Men who want to marry all start out higher earning, even among men who marry by 20.
So the single guys who remain at each stage of average income are the ones who just aren’t making the financial leaps upward. Single women have it even worse, they don’t hit that 50k peak until their 50s, and are down in the 40k range through most of their working years, below married women and single men.
One interesting set of interpretations is that married women on average expect married men to be the ones to take income over benefits and generous leave while they expect to not have to choose and thus don’t. And men who want to marry won’t if they aren’t pretty confident they can decisively earn 60% or more of the household income.
Data reference is from here, covering people who were born in the 1990s as the youngest end of the spectrum.