What is a quarter to 4?

"Quarter to 4" is a way of telling time. It refers to a time that is 15 minutes before 4 o'clock, or 3:45 in the afternoon or evening. It can also be expressed as "3:45 pm" or "15 minutes until 4". The phrase "quarter" comes from the division of an hour into 15-minute increments. This is known as quarter-hour or quarter-past.