I want to know the total duration of iphone alarm. For how long does an iphone alarm rings until it goes off by its own, because in the middle of my early morning sleep, it gets hard for me to wake up, so want to know for how long does an iphone alarm persists until it goes off by its own.

Sometimes i may not wake up by the time alarm stops by it self and is there a way to calculate for how long does an iphone alarm persists until it goes off by its own?