(as) free as air
1. Unencumbered. The phrase means the same as "free," but with more emphasis. I'm as free as air this Friday! Do you want to meet for dinner? She's single now—free as air!
2. Happy and untroubled. Betty must be free as air because I never see her in a bad mood.
(as) free as (the) ˈair/as a ˈbird
completely free: You can’t imagine what it’s like to feel as free as the air. Nobody who hasn’t been in prison can imagine it.