The calendar design of the general mechanical watch is 31 days as a cycle. Therefore, in each small month with only 30 days, the date numbers must be manually moved forward by one day. The perpetual calendar will automatically jump to the 1st of the next month according to whether the end of the month is the 31st day of the big month or the 30th day of the small month. A perpetual calendar that can automatically adjust the date of February 29th in leap years every 4 years is called a "big perpetual calendar".On the contrary, it cannot be displayed as February 29 in leap years, and the date that needs to be adjusted every 4 years is called a "small perpetual calendar".

However, the perpetual calendar is not really "ten thousand years", because every 200 years, there will be a leap year in February with only 28 days. The next leap year with only the 28th of February is 2100, and the last leap year with only the 28th of February is 1900. Both quartz watches and mechanical watches have perpetual calendar products. However, the mechanical perpetual calendar is more expensive due to its complex structure, and the "big perpetual calendar" of the mechanical watch is relatively more complicated than the "small perpetual calendar", so it is also more expensive.