Ah, my bad. So, 60 cumulative hour limit in a rolling 168-hr window. Not sure there's a calculator for that other than just looking at your trips for such conflict (or using the rules auditor)

... unless you mean the 60 degrees longitude rule?

If a flightcrew member travels more than 60 degrees longitude in a FDP or series of FDPs and is away from home base for 168 consecutive hours, the crewmember must be given 56 consecutive hours of rest upon return to home base that must encompass 3 physiological nights based on local time. A physiological night’s rest means 10 hours of rest that encompasses the hours of
0500 and 0700 at the flightcrew member’s home base, unless the individual has acclimated to a different theater.