Full name: tropical year
Plural form: years
Symbol: yr
Alternate spelling: tropical years
Category type: time
Scale factor: 31556925.445
The SI base unit for time is the second.
1 second is equal to 3.1688765172731E-8 tropical year.
Valid units must be of the time type.
You can use this form to select from known units:
The mean tropical year is defined as the period of time for the mean ecliptic longitude of the Sun to increase by 360 degrees. Since the Sun's ecliptic longitude is measured with respect to the equinox, the tropical year comprises a complete cycle of the seasons; because of the biological and socio-economic importance of the seasons, the tropical year is the basis of most calendars.
The International Union of Pure and Applied Chemistry and the International Union of Geological Sciences have jointly recommended using defining the annus, with symbol a, as the length of the tropical year in the year 2000:
a = 31556925.445 seconds (approximately 365.24219265 ephemeris days)
We default to using the Gregorian year on this site, but you can select a specific type of year by entering the full name like "tropical year".