(HOUR(gmt)-HOUR(ldt))
+ (24 * (ABS((YEAR(gmt)*10000+MONTH(gmt)*100+DAY(gmt))
   -(YEAR(ldt)*10000+MONTH(ldt)*100+DAY(ldt)))
/ ((YEAR(gmt)*10000+MONTH(gmt)*100+DAY(gmt))
   -(YEAR(ldt)*10000+MONTH(ldt)*100+DAY(ldt)))
))
+ (MINUTE(gmt)-MINUTE(ldt))/60

To use it, 3 columns are required:

• A Math column that uses the Now special value to obtain the Users current local time. This is used as ldt in the formula.
• A Template column that takes the Users current time and appends the GMT suffix. This is used as gmt in the formula.
• A Math column with the above formula.

The result should be a number, which represents the difference in hours between the users local time and UTC.