Convert days to months (2024)

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

Day

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.

Month

Definition: A month (symbol: mo) is a unit of time used with calendars that approximates the period required for the moon to revolve around Earth. A lunar month lasts approximately 29.53 days, where days are defined based on the SI (International System of Units) base unit of seconds. The Gregorian calendar is the most widely used calendar worldwide, with 365 days (366 in a leap year), 30 or 31 days in each of its 12 months, and 28 or 29 days in February depending on whether or not the year is a leap year.

History/origin: Numerous different calendars have been used throughout history with varying definitions of what constitutes a month. Some of these were lunar calendars based on the monthly cycles of the moon, others were solar calendars that indicated seasons based on the position of the sun relative to the stars, and some were lunisolar calendars that dictated the phase of the moon alongside the time of the solar year.

The Gregorian calendar, currently the preferred calendar for civil use, is a reformed version of the Julian calendar which originated from the ancient Roman calendar. It was introduced in 1582 as a reform to the previous Julian calendar which drifted with respect to the equinoxes by 11 minutes per year, which by 1582, resulted in a difference of 10 days from what was expected. In comparison, although the Gregorian calendar is imperfect, it has an error of 1 day in 3,030 years with respect to the current value of the mean solar year, rather than 1 day in 128 years.

Though there have since been proposals to further reform the calendar (to make it even more accurate), the Gregorian calendar is deeply ingrained in civil use and shows little sign of changing, barring any new significant discoveries.

Current use: The month is still used in various forms throughout the world. The most common is the use of a month within the Gregorian calendar. Certain cultures, such as that of the Chinese, use a lunisolar calendar in addition to the Gregorian calendar. Chinese New Year for example occurs at a different time each year. Other types of months are also used within astronomy, but the most typically understood form of the month is that of the Gregorian calendar.

Day to Month Conversion Table

How to Convert Day to Month

1 d = 0.0328767123 month
1 month = 30.4166666667 d

Example: convert 15 d to month:
15 d = 15 × 0.0328767123 month = 0.4931506849 month

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