How can I find out the total number of hats I have across all of my accounts?
I'm not looking for the number of Unique Hats - that is easy to find.
Just go to your profile, the click on "Account", then click the blue hat with the number on it.
Then select any hat that you have earned then it will tell you what it is, how you got it unless it's a secret hat, and on which site(s) you got it from. You have as of this answer, 17 unique hats and 84 total hats earned. Of course, there is good old fashioned counting.
The Easiest Way
Then go to leader boards,
Then Whole SE network
Then its the 1st one, then hover over your name. Apparently I have 23 hats. Thanks @balpha!
If it's complete total, do some counting, and count the total amount of notifications on your snowflake.
Or you could do some more math and count how many times you earned a hat then add all of them.
Find out on your profile.
Then see that for all of them, then add all of them.
EX: bleh has
4 I am your father's 6 Just here for the hat's 2 925's +_______ =12 total hats