At the very least it should be $10.80 - the last increase was in 2009 to $7.25, and that’s what it would be if it kept up with inflation. If you pegged it to inflation at earlier points then it would be even more today. The minimum of $3.35 in 1981 would be equivalent to $12.35 today. Any future increase in the federal minimum wage should be set to automatically increase with inflation every year. That way it can’t stagnate for 16 years like it currently has.

Realistically the minimum wage would need to be higher in some places at the local level, in particular in some cities where the cost of living is much greater than the national average. The California minimum wage is $16.50, and it’s higher in more expensive cities (Berkeley is $18.67).