Minecraft wiki entry for Hourly_clock, associated text: Using a hopper clock with 128 items will result in an output being sent out every 1 in game hour. It takes approximately 50.02 seconds for 128 items to travel from one hopper into another. Using this method results in a more compacted design for an hourly clock configuration can be done in any way. The video below shows how using droppers and comparators to display the hour.