Double time means 2× your regular rate. California requires it after 12 hours in a single workday, and after 8 hours on a seventh consecutive day. Federally, double time is policy-driven, not legally required.
$
hrs
$22.00/hr
$44.00/hr
$176.00
4.0 hours · 2×
At your regular rate, those 4.0 hours would have paid $88.00. Double time adds $88.00 on top.
Federal FLSA does not mandate double time. California is the major exception:
For any hour worked beyond 12 in a single workday.
For any hour beyond 8 on the seventh consecutive day of the same workweek.