Interval arithmetic provides a robust method for automatically monitoring numerical errors and can be used to solve problems that cannot be efficiently solved with floating-point arithmetic. This paper presents the design and implementation of a combined interval and floating-point comparator/selector, which performs interval intersection, hull, mignitude, magnitude, minimum, maximum, and comparisons, as well as floating-point minimum, maximum and comparisons. Area and delay estimates indicate that the combined interval and floating-point comparator/selector has 98% more area and a worst case delay that is 42% greater than a conventional floating point comparator/selector. The combined interval and floating-point comparator/selector greatly improves the performance of interval selection operations.