Question

How many years does it take for the calendar to repeat itself?

Answer 1

in a regular year the calender repeats in a 28 years cycle
first it repeats after six years and then for two spans of 11 years

Answer 2

Well, it goes like a cycle of  11+11+6, provided it must be a regular year (not a leap year).
For example,
Let's take an instance to year 2019. Then, take a look...
Compare these years:
2002;                17 years before         + 11 years
2013 ;                 6 years before         + 11 years
2019 .               selected year            + 6 years
Their weeks, days and its dates are all the same!!