Simply select the starting city and the desired destination city from the provided list, and enter the current time in the starting city. The calculator will then display the current time in the destination city and the time difference between the two cities. The city and timezone information is taken from a handbook Cities Handbook, which can be updated by any registered user.
This calculator is particularly useful for travelers, international business people, or anyone who needs to coordinate activities across multiple time zones. Note however, that results can be wrong if cities are from different countries due to different winter/summer time change dates.