What is quarter till 4?

Quarter till 4 is a way of expressing time in relation to the hour of 4 o'clock. It means that it is 15 minutes before 4 o'clock. Another way to express this time is as 3:45, as 3:45 is exactly 15 minutes (or a quarter of an hour) before 4 o'clock. Quarter till 4 is commonly used in informal conversations, but it may not be as precise as using the exact time, especially in situations that require punctuality or scheduling.