Set a timer for 3 hours to wake you up in 3 hours. This is a free and easy-to-use countdown timer that allows you to set the hour, minute, and second for the online countdown. Simply start the timer, and it will alert you when 3 hours have passed. Alternatively, you can set a specific date and time to count down to (or from) an event. Begin your 3 hours timer now for a quick and precise reminder.