How Long Is a Tropical Year / Solar Year?

A Year Is Never 365 Days Long

A tropical year, also known as a solar year, an astronomical year, or an equinoctial year, is, on average, approximately 365 days, 5 hours, 48 minutes and 45 seconds long (365.24219 days).

How Long Is a Day on Earth?

A tropical year can be measured from either the vernal or autumnal equinox to the next one, or from the Summer or the winter solstice to the next one.

On timeanddate.com, we calculate a tropical year from the March equinox to the next March equinox (see table below).

Leap Day Synchronizes Calendar

Although a common year has 365 days in today's Gregorian calendar, we add a leap day nearly every four years to stay in sync with the tropical year.

Is There a Perfect Calendar?

Without the correct amount of leap years, our calendar would quickly become out of sync. This happened to the Julian calendar, which had too many leap years. Eventually, it was replaced with the Gregorian calendar.

Can Vary by 30 Minutes

The exact length of a tropical year can vary by up to around half an hour. For instance, the tropical year 2032 will last longer than 365 days and 6 hours. 2027, however, will only last 365 days, 5 hours, and 39 minutes.

List of all tropical years 1900–2100

Length of Tropical Year 2010–2030

Tropical year measured from/to the March equinox. Accuracy believed to be within a few seconds. Leap seconds are accounted for.

Tropical years from 1900 to 2100

Topics: Timekeeping, Calendar, Leap Year, Astronomy, Seasons