Lunar Calendar

Cakeday fully supports the Chinese lunar calendar (also known as the agricultural calendar or Yin calendar), making it easy to track birthdays for people who celebrate on their lunar date.

Switching Calendar Type

When adding or editing a birthday, you will see a segmented picker at the top of the date section with two options: Solar and Lunar. Tap “Lunar” to switch. The picker provides haptic feedback to confirm your selection. All date fields below will immediately update to the lunar format.

Picking Month and Day

In lunar mode, the month picker shows lunar months 1 through 12 (displayed in Chinese as 正月, 二月, etc.). The day picker shows valid lunar days 1 through 29 or 30 depending on the selected month and year. Selecting a different month may adjust the available day range automatically.

Leap Month

The Chinese lunar calendar occasionally has a leap month (闰月). Leap months can only occur for months 2 through 11. The first month (正月) and twelfth month (腊月) never have leap months, and Cakeday enforces this in the date picker.

When a specific year is selected, Cakeday validates whether the leap month actually exists for that year. If the selected year does not have a leap month, the toggle is automatically disabled.

When the birth year is left empty, Cakeday cannot verify which leap months are valid. If you select a leap month without a year, the app shows a warning reminding you that the leap month may not exist for the person’s actual birth year. The entry is still saved, but you should verify the date if the year becomes known later.

Year-less Birthdays

If you do not know the birth year, you can leave it empty. For solar birthdays without a year, Cakeday uses the reference year 2000 internally for date calculations. For lunar birthdays without a year, the current year is used instead, since lunar month lengths vary by year. In both cases, only the month and day are tracked for countdowns.

Automatic Solar/Lunar Conversion

Cakeday converts between solar and lunar dates internally. When you add a lunar birthday, the app calculates the corresponding solar date for countdowns, notifications, and calendar display. The detail view always shows both the solar and lunar dates side by side. Since the lunar calendar shifts relative to the solar calendar each year, the solar date of a lunar birthday will be different every year.

Lunar Date Display Format

Lunar dates are displayed using traditional Chinese format, such as 正月十五 (first month, fifteenth day) or 八月初三 (eighth month, third day). This applies to the birthday detail view, list view, and widgets.

Sexagenary Year Cycle

When the birth year is recorded, the detail view also displays the traditional Chinese sexagenary cycle (干支) for that year, such as 甲子年 or 丙寅年. This 60-year cycle combines the 10 Heavenly Stems and 12 Earthly Branches and is a traditional way to denote years in the Chinese calendar.