Lunar Solar Date Calculator

Lunar Solar Date Calculator helps Estimate a date, age, or timing scenario with simple English inputs and results.

Solar year

Solar month

Solar day

Conversion engine: Intl ko-u-ca-chinese
Leap month flag: Ordinary lunar month

Solar date

February 17, 2026

Lunar date

1/1

D-day from Jan 1 2026

D-47

Next occurrence

February 17, 2026

2026-02-17

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Lunar solar date calculator guide

This English page translates the Korean lunar-solar converter and calls convertSolarToLunar, buildFormattedConversion, and findNextSolarOccurrence. It uses the same Intl.DateTimeFormat calendar key, ko-u-ca-chinese, rather than a simple month-offset stub.

Solar and lunar calendar basis

The solar calendar follows the Gregorian year of about 365.25 days. The Korean lunar calendar is a lunisolar system that follows lunar months of about 29.5 days and periodically inserts leap months to keep seasons aligned.

Because lunar dates shift against the solar calendar every year, a lunar birthday, memorial day, Seollal, Chuseok, or traditional event date must be converted for the target year. A fixed solar month and day is not enough.

Conversion and D-Day output

For solar to lunar conversion the page converts a valid ISO date into a Korean Chinese-calendar date, extracts year, month, day, and leap-month status, then formats D-Day information from a stable reference date. The D-Day label uses D-Day, D-n, or D+n.

For future planning the Korean library searches up to 20 years ahead for the next solar occurrence of the same lunar month and day. This is useful for annual reminders where the lunar date stays fixed but the solar date changes.

Leap month cautions

A leap month is not simply an extra day. It is an extra lunar month, and some families treat leap-month birthdays or memorial days differently from ordinary lunar-month dates.

For legal deadlines, registration dates, contracts, school dates, and government documents, use the official solar date. The lunar converter is for cultural, family, memorial, and traditional-calendar planning.