A calculator can turn a mileage balance into a dollar figure almost instantly. The harder question is what that figure represents. Is it the cost of buying the miles, the price of a flight they could cover, or an offer from someone interested in the rewards? Those are different measurements, even when they appear beside the same account balance. An airline miles calculator becomes useful when it makes that distinction clear. Instead of searching for one supposedly permanent value, evaluate the outcome available to you: how much expenditure a redemption avoids, what costs remain, and whether the reward fits your plans. The following examples are hypothetical and use U.S. dollars throughout. Decide Which Kind of Value You Are Measuring Start by separating acquisition cost, redemption value, and quoted cash value. Acquisition cost describes what you spend to obtain additional miles. Redemption value measures the expense an award replaces. A cash quote is an offer with its own terms...