Julian Years to Months (a to mo)
1 Julian year equals 12.00024641 months (rounded).
How to convert Julian years to months
To convert Julian years to months, multiply the number of Julian years by 12.00024641. The factor is rounded to 10 significant digits. To go the other way, multiply months by 0.08333162218 (rounded).
months = Julian years × 12.00024641
Example: 10 Julian years = 120.0024641 months.
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
Julian Year (a)
Exactly 365.25 days (31,557,600 seconds). The astronomical standard; a light-year is defined using it.
Astronomers wanted a year that would never change, so they borrowed the average length of the old Julian calendar year: exactly 365.25 days of 86,400 SI seconds, or 31,557,600 seconds. The symbol is a, or aj when it must be told apart from other years. It is not an SI unit, but the IAU lists it among the non-SI units accepted for use in astronomy.
The mean tropical year drifts slightly from one year to the next, so it makes a poor unit, whereas the Julian year is constant because it rests on the SI second. It still approximates both the sidereal and tropical years to within about 0.008 days. The current standard epoch, J2000.0, is exactly 12:00 TT on 1 January 2000, and other Julian epochs are counted in Julian years from it. The light-year is defined as the distance light covers in one Julian year.
1 Julian year = 31,557,600 seconds (exactly).
Sources: Wikipedia: Julian year (astronomy); Wikipedia: Light-second; NIST SP 811 Appendix B.8: factors for units outside the SI
Month (mo)
One twelfth of an average Gregorian year: 30.436875 days. Calendar months actually range from 28 to 31 days.
Month and Moon are cognates, and the unit began as the Moon's cycle of phases, about 29.53 days from one new moon to the next. The trouble is that 12 of these fall short of a solar year, so calendars have had to choose. The Islamic calendar stays purely lunar, so its year is about 11 days shorter than the solar year, while the Hebrew calendar is lunisolar, using a 19-year cycle with an extra month. Even the start of a lunar month is still debated between observing the crescent and calculating it.
Gregorian months are a compromise that drifted far from the Moon. Their lengths run from 28 to 31 days, and this site uses their mean of 30.436875 days, one twelfth of the average year. The names also keep Roman history: September to December preserve the Latin numerals for seven to ten, since they were originally the seventh to tenth months, and Quintilis and Sextilis were renamed for Julius Caesar and Augustus. When a contract says month, check whether it means a calendar month or thirty days.
1 month = 2,629,746 seconds (exactly).
Sources: Wikipedia: Month; Wikipedia: Lunar calendar
Related conversions
- Months to Julian years (reverse)
- Julian years to seconds
- Julian years to minutes
- Julian years to hours
- Julian years to days
- Julian years to weeks
- Julian years to years
- Seconds to months
- Minutes to months
- Hours to months
- Days to months
- Weeks to months
- Years to months
- Milliseconds to months
- Microseconds to months
- Nanoseconds to months
- Decades to months
- Centuries to months
- Millennia to months
See all time units.