The megasecond (Ms) is a unit of time in the International System of Units, defined as 106 seconds using the SI prefix system. Multiples of SI units of time longer than a second including megaseconds are rarely used because the traditional units of time are still almost always used. One megasecond is approximately 11.6 days. If megaseconds are used, it would be used to specify lengths of events that last for weeks, months, or years. One mean Gregorian month is about 2.63 Ms and one mean Gregorian year is 31.557 Ms (31.536 Ms in common years and 31.6224 Ms in leap years).