I think this depends on what you consider "calculus." In the philosophy of mathematics there are different perceptions of what mathematics "is." This extends to the disciplines of mathematics.
If you are speaking of the formalized calculus utilizing predicate logic, then I don't think a great many people use this in real life. However, if you mean the principles of calculus: the reasoning of continuity, the concepts of slope and area under a curve, etc., then I would say we utilize calculus in real life. I would say even young children utilize calculus, it is just not in the formalized construction. And I also think that operations of formal schooling discourage students from pursuing this reasoning because it doesn't fit in the box of national assessments.
I think people intuitively utilize the Intermediate Value Theorem. If I said, I took a year off to bike from New York (day 0) to Buenos Aires (day 365), you would possibly ask a series of questions based on reasoning that relates to IVT, even if you don't know what IVT is. You know that to get from New York to Buenos Aires, I would have to travel a continuous path through a set of latitudes. You would pose questions that seemed reasonable, "Did you stop in Panama City?", because you know that I would have to pass through that latitude at some point on my way. Of course, that doesn't mean I didn't make a side trip to Montréal.
This can also come up in trials. For example, the evidence is a set of skid marks 200 feet from a house damaged by a car that collided into it. A fire hydrant between the skid marks and the house is broken. A witness remembers seeing the car making the skid marks, but doesn't know if the car hit the fire hydrant. Is it likely that this car broke the fire hydrant?