how long is the concert , so i will bring the right amount of oxygen

Was just at one there. It lasted 4 1/2 hrs.

Counting the wait to get in, the concert and the time to get out, 6 hours "should" be enough.

I'm no doctor..cant give advice on that.

Definitely depends on the show. May 7th had 4 different bands. Most will be 3 to 4 hours total.

Went may 7th. 6:30 to 11:30 ish.

Depends on the concert. Each person is different. How many openers. Etc. I went to one that was over 4 hours and the one before was 1.5 hours.