$300 to Cancun? How to Tell When a Flight Really Is a Good Deal
Find the hidden gems
Note: I know no-one is flying right now, but hopefully soon we‘ll be able to start thinking about holidays and family trips again.
Ever seen a tweet advertising a great flight deal, only to discover the flight is just $10 cheaper than it would be on any other day? How can you tell, out of dozens of flight deals you see every day, which ones are actually worth it? You can do the same thing the airline’s accountants do: calculate the Cost Per Mile.
The internet is full of websites and Twitter accounts that regularly post flight deals. Some of them are really good, especially if an airline employee makes a mistake when entering prices. But those occasions are rare, and you have to be very quick to book and hope the airline doesn’t decide to cancel your ticket because of the mistake.
Many times, the airline just happens to have a sale, and if you’re flexible enough you can travel at a low price — but it’s only a bit cheaper than a regular ticket and can hardly be called a “great deal”.
Why Does Cost per Mile Matter?
The cost per mile is how much it costs the airline to offer a seat on the flight, including things like fuel, ground handling, and employee costs.
According to this analysis done by consultancy firm Oliver Wyman, in 2018 US domestic airlines had an average cost of about 12 US cents per mile flown. The average ranges from 8 cents per mile for low-cost carriers like Spirit and Frontier, to 13 cents per mile for American and Delta.
So, to figure out if you’re getting a good deal, you can calculate the cost per mile for your flight and compare it with the average costs for the type of airline you’re flying. If you see a flight that works out to less than 8 cents per mile on Spirit, or less than 12 on American — the lower the better — it’s probably a good deal.
Let’s walk through an example to see if it checks out.
Running the Numbers
To calculate the cost per mile, you need to find out the distance between the two airports. Since the Earth is round, the shortest distance isn’t a straight line but an arc — called the Great Circle Distance.
I recommend using the GCMap website for this — all you need to do is enter the two airport codes and it will show you the corresponding distance. Here’s how it looks for New York to San Francisco:
Note: If the deal is for a return flight, don’t forget to double the number of miles.
To test out this method, I searched on Google Flights for a weekend trip from New York City to anywhere in the US during the month of October (fingers crossed we can travel again by then):
On the left-hand side, you can see the top five suggestions — the prices are for a round-trip flight:
- Miami for $173
- Chicago for $89
- Las Vegas for $173
- New Orleans for $161
- Toronto for $113
Now, let’s work out the Cost Per Mile for each of these:
- NYC-Miami: $173/1089 miles each way → 7.2 CPM
- NYC-Chicago: $89/740 miles each way → 10.6 CPM
- NYC-Las Vegas: $173/2248 miles each way → 3.4 CPM
- NYC-New Orleans: $161/1182 miles each way → 6.6 CPM
- NYC-Toronto: $113/366 miles each way → 21.4 CPM
Even though the flight to Chicago is the cheapest, we can see from the numbers Las Vegas is the best deal by far at just 3.4 cents per mile. To validate your results, you can click on the flight details, and Google will tell you if it’s cheaper than usual based on historical data they collect:
Note: this method will always show better results for longer flights since the airport and security fees are the same no matter how far you’re flying.
So there you have it, an easy way to compare flight prices and pick out great deals. Good luck and safe travels!
