If you still live at home, I wouldn't mention it. One, it's personal and two, he could make your life a living hell until you move out. If he asks you about it, you might say something. Other than that, you don't need to announce that you're bisexual. It's no one's beeswax but your own.
OK so, I want to come out to my dad as bisexual. I just don't know whether he is homophobic or not. When I saw a picture of his cousin and his husband and said aw he said " don't say aw, they're gay". How do I tell if he is or not? Please help.
Unless you are 18, there is no need to voice your sexuality. When you are 18, feel free to do whatever you want and say whatever you want. You'll be of age to deal with the consequences and make decisions to deal with them. Just know that not everyone will support you, and sometimes that means it's the ones that you are the closest to that end up being the ones that you will drift furthest from. Good Luck