There chances of contracting HIV from unsafe sex is very high. The semen and vagina liquid have the tendency to carry the HIV germs. So if your partner has HIV then there is strong possibility that you will be affected by it.
Very very high
Its difficult to say, if the person you have sex with does not have HIV, you might be safe, but if you have unprotected sex with a hiv person, I think the chance of contracting hiv is pretty high, about 80-90%.