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Convert days to years

Please provide values below to convert day [d] to year [y], or vice versa.



Definition: A day (symbol: d) is an accepted, non-SI unit of time that is defined based on the SI (International System of Units) unit of time, the second, and is equal to 86,400 seconds.

History/origin: The term "day" originates from the Old English term "dæg." It is approximately equal to the period required for the Earth to complete a full rotation with respect to the sun. This was later re-defined in terms of the second in 1960, when the second was redefined in terms of Earth's orbital motion in the year 1900. The second, and therefore the day, was again re-defined in 1967 by atomic electron transition.

Current use: The day is a term used worldwide within many contexts one of the most common of which is to refer to a time interval of 24 hours. It is also used to reference daytime, or the period of time during which the sun is above the horizon. The term also has other colloquial uses such as the day of the week and fixed clock periods like 6:00 am to 6:00 pm, among others.


Definition: A year (symbol: y, yr, or a) is a measurement of time based on Earth's orbital period around the sun. This is approximated as 365 or 366 days in the Gregorian calendar. Earth's orbit around the sun is seen as the passing of seasons in which weather, daylight hours, vegetation, and soil fertility, among other things, change.

History/origin: Various definitions of a year have been used by different calendars throughout history. The most commonly used calendar for civil affairs today is the Gregorian calendar, a solar calendar which consists of 365 or 366 days, depending on whether or not the year is a leap year. In astronomy, many other definitions of the year exist, such as the sidereal, draconic, lunar, and Gaussian year, among others.

The Gregorian calendar is a calendar that was reformed from the Julian calendar, which was a calendar that itself was reformed from the ancient Roman calendar.

Current use: The definition of a year based on the Gregorian calendar is used worldwide. In some cultures, lunisolar calendars are also used. In astronomy, many different definitions of the year are used, including the Julian year as a unit of time equal to 365.25 days based on the SI (International System of Units) base unit of seconds.

The term "year" is also used to describe periods that are loosely associated to the calendar year, such as the seasonal year, fiscal year, and academic year.

Day to Year Conversion Table

Day [d]Year [y]
0.01 d2.73785E-5 y
0.1 d0.0002737851 y
1 d0.0027378508 y
2 d0.0054757016 y
3 d0.0082135524 y
5 d0.0136892539 y
10 d0.0273785079 y
20 d0.0547570157 y
50 d0.1368925394 y
100 d0.2737850787 y
1000 d2.7378507871 y

How to Convert Day to Year

1 d = 0.0027378508 y
1 y = 365.25 d

Example: convert 15 d to y:
15 d = 15 × 0.0027378508 y = 0.0410677618 y

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