A clock is shaped like a circle and is composed of 360 degrees. There are 60 minutes in an hour, and 360 degrees divided by 60 minutes is 6. Therefore, the minute hand moves 6 degrees per minute. It takes 720 minutes for the hour hand to move around the clock. 360 degrees divided by 720 minutes is 0.5. Therefore, the hour hand moves 0.5 degrees per minute. See Wikipedia for more details.

This tool will calculate the angles between hour to minute hands and minute to hour hands in a clockwise manner. It will accept hours in either 12 or 24 hour format.