Months to Decades (mo to dec)
1 month equals 0.008333333333 decades (rounded).
How to convert months to decades
To convert months to decades, multiply the number of months by 0.008333333333. The factor is rounded to 10 significant digits. To go the other way, multiply decades by 120.
decades = months × 0.008333333333
Example: 10 months = 0.08333333333 decades.
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
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
Decade (dec)
Ten years.
Greek dekas, a group of ten, gave English decade, and the Latin equivalent decennium survives in words like decennial. The idea of naming whole decades is newer. The convention of grouping years by their tens digit, so that 1960 to 1969 is the 1960s, became common in the late 19th century, and the 20th century then produced a gallery of nicknames such as the Roaring Twenties and the Swinging Sixties.
A decade is ten years, which on this site means ten average Gregorian years. The two counting styles can disagree, in the same way as with centuries: since the AD calendar has no year zero, a strict reading makes the first decade run from year 1 to year 10. A 2019 YouGov poll of 13,582 US adults found 64 percent expected the next decade to be 2020 to 2029, 17 percent said 2021 to 2030, and 19 percent did not know. Most people prefer the zero-to-nine version.
1 decade = 315,569,520 seconds (exactly).
Sources: Wikipedia: Decade; Wikipedia: Year zero
Related conversions
- Decades to months (reverse)
- Months to seconds
- Months to minutes
- Months to hours
- Months to days
- Months to weeks
- Months to years
- Months to milliseconds
- Months to microseconds
- Months to nanoseconds
- Months to centuries
- Months to millennia
- Months to picoseconds
- Seconds to decades
- Minutes to decades
- Hours to decades
- Days to decades
- Weeks to decades
- Years to decades
- Milliseconds to decades
- Microseconds to decades
- Nanoseconds to decades
- Centuries to decades
- Millennia to decades
See all time units.