If he doesn't want to commit, but you do, then what you tell him is goodbye. Relationships are difficult enough when people are on the same page, but when you are on different pages, especially regarding something as serious as commitment, then you look at him and say "This isn't working for me, I want something different, so goodbye".

Most relationships fail because people want different things, are at different times in their lives, and are aspiring for different goals and objectives. You have to respect yourself enough to be able to say, this isn't working for me and I need someone who wants the same things. Simple.

There are a lot of factors to consider. How long have you been casually dating? How much time are you willing to give him to make a decision? Why do you think he doesn't want to commit? Have you had a serious talk with him letting him know that you aren't seeing anyone else but him and want to make it exclusive? Tell him what you want from the relationship. Ask him what he wants. If you two aren't on the same page, maybe it's best to end things. Why stay in a relationship that can't meet your needs.

I personally don't think that you can convince a guy who won't commit to commit. It sounds like you are in a FWB situation and you want to move to a LTR situation and I don't think that can happen. Tell him goodbye and look for a guy who will commit.