TravelMath can figure out all sorts of travel-related calculations, including your travel time so you get to the airport on time or don't miss a connecting flight. Now they have updated to compare the cost of driving versus flying, which is perfect for planning a weekend getaway or holiday travel. Besides the monetary cost, TravelMath also takes the cost of your time into account. So if you'd have to take time off work to drive, it includes the lost earnings in the cost comparison. By default, the calculator uses a cost of $10 per hour, but you can easily input an amount that better matches your hourly rate. In fact, you can input your own numbers for any of the cost estimates so that the end comparison is as accurate as possible.
I gave the calculator a try with a hypothetical weekend trip for two between San Francisco and Los Angeles, a route that people often both drive and fly. I adjusted the time cost rate, and the end result was that it is slightly cheaper to drive since the cost of driving can be split between two people, rather than multiplying by two if we were going to fly. Give the comparison calculator a try for yourself at the link below.