When is it cheaper to fly instead of drive?

Q. - I've been wondering, when is it cheaper to fly somewhere instead of driving there?

A. - The question of whether it’s cheaper to drive instead of fly should be asked a different way: When is it better to drive instead of fly? In other words, we have an assumption about which is the better option because of the price of an airline ticket before we ever think through the answer. I had always assumed that if I could drive somewhere in 4 or 5 hours, that would be the better option than flying. But that was just my assumption.

Because time has value, you might draw the line on how much time you would spend behind the wheel vs. crammed in an airplane seat. For example, where I live in northern Virginia, it would take ~13 hours to drive to Memphis, Tennessee, which is 850 miles. That’s too long to drive in one day, so it requires an overnight stay, which these days can run $150 a night. The gas might be about $100, and a meal, so driving has a one-way cost of ~$300, or $600 round trip. Can I get an airline ticket for less than $600? Generally, I would say yes for most domestic destinations. Searches one month out show tickets are about $450, and because of connections, it takes about 5 hours of flight time. Add in the wait before takeoff and getting out of the airport (another 3 hours), and it’s an 8-hour trip by air door to door. But we also need to add in a meal and airport parking (we’ll assume a weeklong trip @$10 per day for parking), and that adds up to another $100.

So, this weeklong trip costs $600 by car and 26 hours round-trip or $550 by air and 16 hours round-trip. Thus, if our time is limited, we get 10 hours back traveling by air, even though the cost is almost the same. But, this assumes that for the weeklong trip, we didn’t need a car in Memphis. If we did need a car, that would add $300 to the flying option. Now it would cost us $300 extra to save 10 hours. Does that tip the scale to drive instead of fly? How much is your time worth?

In the example, if you were doing this trip, the deal breaker may have been the overnight stay on the road, mostly because of the extra travel time. Certainly, long-distance travel by car has the advantage of flexibility in departure time and fewer hassles than flying, but having to spend the night either lengthens the trip or shortens the time in Memphis. And that might be the key deciding factor in deciding when to fly vs. drive, depending on when we can leave and when we need to arrive.

Now, imagine instead of Memphis, I need to go to Toledo, Ohio. Seems pretty far from Northern Virginia, but it’s only a little over a 7-hour drive. I put the trip into a web airline search, and guess what? I can’t fly from Virginia to Toledo. Why? Because the airlines have evolved their business model to make it almost impossible to get a direct flight to many destinations. They also no longer fly into smaller cities that are less than 100 miles from a hub city. I can go direct, and cheap, from Virginia to Detroit, but not Toledo. Thus, I’d have to rent a car and drive the 40 minutes to an hour from Detroit to Toledo. Because this destination by car doesn’t require an overnight stay, it’s clearly the better option to drive, even though the auto tolls on the Pennsylvania and Ohio Turnpike are pretty high.

As I went through thinking about different destinations and whether it’s better to drive instead of fly - considering time and cost - the simple rule of thumb today seems to be: if you’re going less than a long day’s drive away (~650 miles), it’s better to drive rather than to fly. I used to think there was no way I’d drive to Toledo because it shouldn’t be more than a 2-hour flight, but that was before airlines evolved away from smaller markets and increased the time you’ll spend getting through airports and the cost of getting to or parking there. Of course, if your employer is paying the tab, you care less about the trip cost and more about your time, so the calculation might be different. But for personal travel, consider my simple “long day’s drive” rule if you don’t want to crunch numbers.

I believe this “long day’s drive” rule also applies whether you live 20 minutes from a major airport or you live in Toledo and must always drive an hour to Detroit, which adds time to every trip by air. When going longer than a “long day’s drive” or more than a few days and requiring a rental car or long stay at airport parking you might want to do some number crunching on a napkin due to the variable costs of the particular trip - price of airline ticket, cost of gas, how many meals on the road, airport parking or taxi both ways, etc. The options could be several hundred dollars apart, and you’ll be inclined to choose the cheapest one. And of course, there’s the wear and tear on your car, but also a higher likelihood of airline travel delays, making it a challenge to base the decision on any one factor. In general, driving to a destination is a better choice when it’s less than a “long day’s drive”.