Time Converter

Time is the SI quantity with the longest history of measurement, and its units are among the few that predate the metric system yet remain universally used. The second is the SI base unit of time; minutes, hours, and days are accepted for use with SI but are not SI units.

Exact definitions

• 1 minute = 60 seconds exactly
• 1 hour = 60 minutes = 3600 seconds exactly
• 1 day = 24 hours = 86,400 seconds exactly
• 1 week = 7 days = 604,800 seconds exactly
• 1 millisecond = 0.001 seconds
• 1 microsecond = 10⁻⁶ seconds
• 1 nanosecond = 10⁻⁹ seconds

Years and leap years

Unlike seconds, minutes, hours, and days, the year is not an exact number of days. The tropical year (the time between successive vernal equinoxes) is about 365.2422 days. The Gregorian calendar handles this with leap years. M-Convert's year converter uses the conventional 365-day year; use the more specific Julian year (365.25 days) or tropical year when precision requires it.