Travelmath provides an online travel distance calculator to help you measure both flying distances and driving distances. You can then compare the two results to see the difference. Flight distance is computed from a GPS-accurate great circle formula, which gives you the straight line distance "as the crow flies". Driving distance by car is determined from the actual turn-by-turn driving directions. If you want to split the distance with a friend, you can use the halfway point calculator to find the best place to meet. For a long distance trip, you can plan a road trip with stops. Or browse the mileage charts for any state or country. If you just need a quick answer, try the mileage calculator at MileageCalc.com.