What is the best volume to listen to music on iPhone with apple earbuds?

I have a bad habit if listening to loud music. I want to stop that to save my hearing. So I want to know what is a volume that's loud enough but will not kill my hearing.

Turn the volume OFF,
when the headset is comfortable, turn it on and gradually up,
one step at a time. To protect your hearing you want to keep it at the minimum. It can be surprising how much more can be heard at lower settings.

About halfway should be the maximum. When I'm in a car I'd go two more from halfway at max.