Hello. Your expression is not bad in principle, you just picked bad way to count the difference between the timezones. To use the modulo function (%, it returns reminder after division of what is in front of it by what is behind it) correctly on time zones, you need to add positive value of the period to your zone difference from coordinated universal time (UTC). The %12 means you probably want to show the time in 12h format (12h period). For your purpose I would use one field with regular local time #Dh#:#DmZ# and another for Central Standard Time (CST), which is 6 hours behind UTC. It should look more like ((#DUH#+12-6)%12):#DUmZ# (you can count the numbers together when writing the final formula, I just put them both there to make it more understandable)