==TIMEVALUE(time_text)
=TIMEVALUE("2:24 AM")
The TIMEVALUE function takes a text string representing a time and returns its equivalent decimal value. For example, this returns 0.10, which is the decimal part of a day based on the time specified. This is because the day is divided into 24 hours, and each hour is further divided into 60 minutes, so 2:24 AM is equivalent to 2.4 hours or 0.10 of a day.
=TIMEVALUE("22-Aug-2011 6:35 AM")
The TIMEVALUE function can also take a text string containing both a date and a time and return its equivalent decimal value. For example, this returns 0.2743. This is because the date specified is August 22nd, 2011 and the time is 6:35 AM. This is equivalent to 6.58 hours or 0.2743 of a day.
The TIMEVALUE function converts a text string representing a time to a decimal number between 0 and 0.99988426, which corresponds to times from 0:00:00 to 23:59:59.