Where is my birthday day?

I was born on a Wednesday, and for some reason, when my birthday falls on a Wednesday, I always consider it a “special” birthday: a Birthday Day.

It’s been a long time since I’ve had a Birthday Day — almost ten years! When I was 12-13 years old, I did some work to discover that my Birthday Day would be every 5-6 years, but apparently, I didn’t do the math for one more cycle!

There are cycles to Birthday Days, depending on which day of the week the leap year is in relation to the day you were born. The cycle goes 11, 6, 5, 6 years, but the mapping looks sorta like this:

For example, if you were born on January 2, 1980, your first cycle is five years and looks something like this:

It’s interesting to note that during these five years, you wouldn’t have a birthday on a Tuesday or Thursday. Then, after five years, you enter a six-year cycle:

Where you don’t have a Sunday birthday, and finally, you enter the 11-year cycle:

This is the current cycle I am in, and most of my family is as well. I’m near the end of it, but my wife is just entering it. I should note that there is another 5-year cycle, and then the cycles repeat.

I’ve provided one that allows you to configure your settings below so you can see which cycle you are on and when your next Birthday Day is.

PS: note that 2100 is NOT a leap year (century years are only leap years when divisible by 400), so the pattern breaks around that time… 😉


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