Take a look at my new Birthday Converter. Plug in your birthday, and find out what that day is on my calendar, and how old you are in my 300-day years (instead of the 365.249998-day years you’ve been using).
This is similar to my (updated) Calendar converter. The two are available as one .xls file.
I was just playing around with this myself. Did you know that my birthday is 4.3.3? I did. I forgot how old I was, though. I’m 28. I’ll be 29 in a few short months. How old are you?