It seems to vary quite a bit between individuals, often regardless of actual net worth.
When I say "on hand", it's what you carry around, and what's in your apartment/house.
Personally, I have a small stash of USD and CHF (Swiss Franc)- their paper bills are a work of art.
And some physical platinum. All together it's enough to buy groceries for some time :)
I've heard it's a bad idea to have too much physically, something to do with homeowners insurance.
But since I rent, it's a non-issue.
What about you guys / your thoughts?