fly or drive methodology

Airliner Basics

Most of our air travel numbers come from the US Government Bureau of Transportation Statistics (BTS). We are not using the direct numbers published by the Aircraft Makers or Wikipedia since they are mostly “best case” scenarios. Here is how our numbers are calculated,

  1. We try to use a Real World Scenario – Aircraft are most efficient when every seat is occupied – however, the so-called “load factor” (how many seats are full?) is 82%, so we take this into account.
  2. There is quite a bit of fuel (Energy) use for an Airliner to taxi and take off – this is also calculated. A shorter flight has more overhead of this type, while a longer flight has less.
  3. In an ideal situation the longest flight with the plane full is the most efficient. How Efficient?
    Let’s look at the two Airliners we are basing our averages on:
    Airbus 220: 120 Miles per Gallon per seat.
    Boeing 737 MAX-8: 110-120 Miles per Gallon per seat.

Those are very respectable numbers and Airliners will only get better in the future. We can see that, in the best cases, a single person flying a decent distance is getting up to 4X the “MPG” as many cars. Of course, our calculators use a more conservative number so as inform the public in the most accurate way possible.
Here is a fairly complete article on the current Boeing 737 MPG.

Motor Vehicle Basics

This is much simpler since your car usually has a known MPG. If you have an efficient EV, use the higher MPG numbers such as 45 MPG – as you can see on our Vehicle Efficiency Calculator, the efficiency of an EV is similar to that of good Hybrid when the EV is charged from the standard US Grid.

Back to Fly or Drive Calculator

Note: COST is not considered in the calculator, but rather how far you are going on a gallon of liquid fuel. Jets use a fuel which is similar to Kerosene and it does contain about 7% more BTU per gallon than regular gasoline. However, since calculators are not designed to be precise, we are not adjusting for this – rather only calculating miles driven or flown per liquid gallon per person.

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