Around 30 سیکنڈ just holding it, and about a منٹ مزید when I let air out.
The reason it's a منٹ مزید when I'm exhaling it out is because I was in choir, and some of the notes we had were insanely long. I had to freaking teach myself to do that and I ended up being the only person in choir who could hold any of the notes...
Not that anyone cares, but it's a cool story, bro. XD