How to convert a Chinese lunar birthday

Start with the date that you actually know. If a birth certificate gives a Gregorian date, use Gregorian → Chinese lunar to find the lunar year, month, and day. Record whether the result is in a leap month. Do not treat a lunar date written as “8/15” as August 15 on the Gregorian calendar.

To find that lunar birthday in another year, change the converter to Chinese lunar → Gregorian. Enter the target lunar year and the same lunar month and day. The resulting Gregorian date is the date to put in that year’s calendar. If the month or day does not exist, the converter will ask you to choose again rather than quietly move the birthday.

For an important family celebration, check the date with the person whose birthday it is and compare an independent calendar table. The converter can resolve a date; it cannot decide a family’s celebration custom.

Try it step by step

1. Convert the known birth date.
2. Record lunar month, day, and any leap-month marker.
3. Choose the celebration year and convert back.
4. Export that one date, then check it in your calendar.

Convert a birthday →

Sources & further reading

• Hong Kong Observatory — Gregorian–lunar conversion tables

Sources checked 21 September 2026. Written with AI assistance, reviewed by the owner, and checked against the linked material.