Days to Years (d to yr)
1 day equals 0.002737907007 years (rounded).
How to convert days to years
To convert days to years, multiply the number of days by 0.002737907007. The factor is rounded to 10 significant digits. To go the other way, multiply years by 365.2425.
years = days × 0.002737907007
Example: 10 days = 0.02737907007 years.
Months and years are not constant. This site uses the average Gregorian year of 365.2425 days, so one 'year' converts to 365.2425 days, not 365; use 'common year' for exactly 365 days.
About these units
Day (d)
24 hours or 86,400 seconds. The mean solar day; the actual rotation of the Earth is about 4 minutes shorter (see sidereal day).
Old English dæg is the root of our day, with close cousins in German Tag, Dutch dag and Icelandic dagur, all descending from Proto-Germanic dagaz. It is the oldest unit here, because the cycle of light and dark needs no instrument. Yet the day we count is a constructed average: the actual interval from one noon to the next varies through the year by up to about 7.9 seconds, because Earth's orbit is elliptical and its axis is tilted.
Astronomers smooth this out with a fictitious mean Sun, giving the mean solar day, and the day in the SI sense is fixed at exactly 86,400 seconds. Reality has drifted slightly: the mean solar day has recently averaged about 86,400.002 seconds, and tidal drag from the Moon is lengthening it by about 2 milliseconds per century. That is why 27 leap seconds were added to UTC between 1972 and 2022. One rotation measured against the distant stars is shorter, about 23 hours 56 minutes 4.09 seconds, and a year contains one more of these sidereal days than solar days.
1 day = 86,400 seconds (exactly).
Sources: Wikipedia: Day; BIPM: SI Brochure, 9th edition
Year (yr)
The average Gregorian calendar year of 365.2425 days (31,556,952 seconds). A common year has 365 days and a leap year 366.
A year is the Earth's trip around the Sun, but there are several versions. The tropical year, which tracks the seasons, is about 365.2422 days. The sidereal year, measured against the stars, is about 365.2564 days, roughly 20 minutes longer, because the Earth's axis precesses. Calendars must squeeze these into whole days, which is the origin of leap years. English year descends from Old English gear, while Latin annus, the source of annual, comes from a different root.
The Gregorian calendar, introduced by Pope Gregory XIII's bull of 24 February 1582, fixed the problem of Julian drift that had moved the March equinox away from 21 March and upset the date of Easter. Ten days were skipped, so Thursday 4 October was followed by Friday 15 October. Its rule of skipping leap days in century years not divisible by 400 gives a mean year of 365.2425 days, the value this site uses for the year. Britain and its empire switched in 1752 and Russia in 1918. Scientists write the year as a, with the Julian year fixed at 31,557,600 seconds.
1 year = 31,556,952 seconds (exactly).
Sources: Wikipedia: Year; Wikipedia: Gregorian calendar
Related conversions
- Years to days (reverse)
- Days to seconds
- Days to minutes
- Days to hours
- Days to weeks
- Days to months
- Days to milliseconds
- Days to microseconds
- Days to nanoseconds
- Days to decades
- Days to centuries
- Days to millennia
- Days to picoseconds
- Seconds to years
- Minutes to years
- Hours to years
- Weeks to years
- Months to years
- Milliseconds to years
- Microseconds to years
- Nanoseconds to years
- Decades to years
- Centuries to years
- Millennia to years
- Picoseconds to years
See all time units.