I have to level a concrete floor that is more than 2 inches out of level. Should I be using self leveler, or concrete? Is 2" too much for self leveler?
If it is only 2" you should not be using concrete because it's not thick enough. Concrete does not bond to concrete so it will just crack over time.
It may be helpful to make use of a leveler to ensure that all areas have been evenly applied with concrete. Professionals contractors know exactly what to do but if you prefer to do your very own home improvement project, you might try to consider leaving it for a few days for curing and then measure the surface once again to double check if it is even.