Lunar Leap Month Calculator
East Asian lunar regular and leap-month reference
This tool uses browser international calendar data to convert Gregorian dates to lunar dates. Choose a reference region for Korea, China, Taiwan, Hong Kong, Vietnam, or Japan old-calendar use so date boundaries stay consistent. For formal rituals or official schedules, confirm the result against the calendar source you rely on.
Date Result
Month Type
Regular month
This is the ordinary occurrence of the lunar month.
Lunar Date
Sixth month 11, lunar 2026
Gregorian Date
Fri, July 24, 2026
Korea · Asia/Seoul
A regular month and a leap month can share the same lunar month number. For lunar birthdays, memorial days, or planning, check both the month number and the leap-month marker.
Month-by-Month Leap Table
Usage Tips
Check regular and leap lunar months before saving Korean lunar calendar dates
Convert a Gregorian date to an East Asian lunisolar calendar reference date, identify whether the month is regular or leap, and compare the Gregorian ranges for a selected lunar year and month. Use it as a planning reference for lunar birthdays, memorial days, moving dates, and family calendar notes.
What is Lunar Leap Month Calculator?
The Lunar Leap Month Calculator converts a Gregorian date to an East Asian lunisolar-calendar reference date, identifies whether the lunar month is regular or leap, and compares regular and leap-month Gregorian date ranges for a selected lunar year and month. Because lunisolar calendars occasionally repeat a lunar month number to stay aligned with the seasons, the same lunar month number can have both a regular range and a leap-month range. Choose a reference region for Korea, China, Taiwan, Hong Kong, Vietnam, or Japan old-calendar use, then use the result as a planning reference for lunar birthdays, memorial days, family calendar notes, moving dates, and other schedules where the regular/leap month distinction matters.
How to Use
- 1Choose the reference region whose time-zone date boundary should be used.
- 2Select a Gregorian date to see its lunar year, month, day, and month type.
- 3Enter the lunar year and month you want to check for a birthday, memorial day, or family schedule.
- 4Review the year summary to see whether that lunar year has a leap month and which month repeats.
- 5Compare the selected month's regular Gregorian date range with its leap-month range, if one exists.
- 6Scan the month-by-month leap table for the selected lunar year.
- 7Copy the result for calendar notes, family schedules, or planning records.
Check the lunar month number together with leap-month status
Last reviewed: July 11, 2026Solar-date lunar lookup
solar date + selected time zone → Intl Chinese calendar → lunar year, month, day, and isLeapMonth
The browser calendar data is evaluated at the selected regional date boundary, then leap-month status is kept as a separate flag.
Converting the Gregorian date for Lunar New Year 2024
- • Gregorian 2024-02-10
- • Korea time zone Asia/Seoul
- • Read lunar date and leap status
- 1. The Chinese-calendar data returns lunar year 2024, month 1, day 1
- 2. The month text has no leap prefix, so it is a regular month
2024-02-10 is regular lunar month 1, day 1 of lunar year 2024 in the Korea reference.
How to read the result
- When a year repeats a month such as leap sixth month, record regular or leap status alongside the month number.
- The regional choice selects the date boundary and Intl time zone reference rather than a completely different calendar system.
Conditions that change the result
- Results depend on browser Intl calendar data and are limited to the supported 1900–2100 range.
- For religious, institutional, or family observances, compare the result with the calendar source actually used.
Common input mistakes
- Treating regular sixth month and leap sixth month as one period can shift a Gregorian appointment by weeks.
- Comparing dates near midnight without the intended time zone can produce a different boundary-day result.
Reference Knowledge
- ●The calculation uses browser Intl Chinese calendar data and evaluates dates in the selected reference region's time zone.
- ●The reference region does not switch to a completely separate national almanac. It controls which regional date boundary is used for the shared East Asian lunisolar-calendar style calculation.
- ●A regular month is the ordinary occurrence of a lunar month number. A leap lunar month repeats the same month number after the regular month.
- ●Not every lunar year has a leap month. Leap months are inserted only when needed to keep the lunar calendar aligned with the solar year.
- ●When a leap month exists, the month number alone can be ambiguous. Month 6 and Leap Month 6 can refer to different Gregorian date ranges.
- ●The supported range is limited to 1900 through 2100 to reduce long-range differences across browser calendar data.
- ●For rituals, official schedules, or high-stakes planning, compare the result with the calendar source, institution, or family convention you use.
FAQ
Q.What is the difference between a regular month and a leap month?
A regular month is the ordinary occurrence of that lunar month. A leap month is an inserted repeat of the same lunar month number, so Month 6 and Leap Month 6 are different date ranges.
Q.Can a single Gregorian date tell me whether it is in a leap month?
Yes. Once the Gregorian date is converted to a lunar date, the calendar data indicates whether the lunar month is regular or leap.
Q.Is this always identical to every regional lunar calendar?
The tool uses browser international calendar data with the selected reference region's time zone. It is useful for everyday checks, but important dates should still be verified against the calendar source or institution you rely on.
Q.Does every lunar year have a leap month?
No. Leap months are inserted only in some lunar years to keep the lunar calendar aligned with the solar year.
Q.How should I check a lunar birthday that falls in a leap month?
First check whether the target lunar year contains the same leap month. If it does not, families may follow different customs, such as observing the regular month or another agreed date, so use the result together with your family convention.
Q.Why do regular and leap lunar month ranges change each year?
Lunar months follow moon cycles, while Gregorian dates follow the solar year. Because the calendars are based on different cycles, the Gregorian range for the same lunar month shifts from year to year, and leap-month years can repeat one month number.
Q.What changes when I choose a different reference region?
The selected region controls the time-zone date boundary used for conversion. This keeps results consistent for users in different countries while letting them check Korea, China-region, Vietnam, or Japan old-calendar reference use cases.
