Every few weeks, an airline sends out an email. I mean, the inspiration for this article actually came from that same email! You know what I’m talking about…the ones that start with:
"Buy miles with a 100% bonus!"
"Limited-time promotion!"
"Lowest price of the year!"
To many travelers, these offers seem irresistible.
After all, if airline miles can be redeemed for expensive flights, buying them at a discount sounds like a smart financial decision. In reality, most travelers should almost never buy miles.
Here's why.
Miles Are Not an Investment
One of the biggest misconceptions in award travel is treating miles like an asset.
They're not.
Miles are a loyalty currency controlled entirely by the airline. Unlike cash, stocks, or even gift cards, you don't own the underlying value…the airline does.
And the airline can change the rules whenever it wants.
The Devaluation Problem
Airlines routinely increase award prices. This can happen sometimes quietly or even simply overnight.
A flight that costs 60,000 miles today might cost 80,000 miles next year (or even in a few months time!). This is called a devaluation.
And it's one of the biggest risks of holding large mileage balances.
Imagine purchasing $1,000 worth of miles today only to discover your intended redemption now requires 25% more miles six months later.
That's a risk most travelers never consider.
You're Giving Airlines an Interest-Free Loan
When you buy miles without a specific redemption in mind, you're effectively giving the airline money today in exchange for a promise of future value.
The airline gets:
Immediate cash
No obligation to provide a specific flight
Full control over future pricing
You get:
A currency that can lose value
Limited redemption options
No guarantee your preferred flights will be available
That's not a particularly attractive trade.
The Math Often Doesn't Work
Many airlines sell miles for approximately 2 to 3 cents each. Yet many redemptions produce less value than that.
Example:
You buy 50,000 miles for $1,250. You redeem them for a flight that would have cost $900.
What does that mean for you?
It means you effectively just paid more than the ticket was worth. This happens more often than most people realize. The excitement of "using miles" can distract travelers from evaluating whether the economics make sense.
The Exception: Buying Miles for a Specific Redemption
There are situations where purchasing miles can be rational.
Let's say:
A business-class ticket costs $4,000
The same flight costs 75,000 miles
You can purchase the missing miles for $1,200
In this case, buying miles may unlock significant savings. The key difference is that the redemption already exists. You are buying miles to immediately spend them…not to hold them.
This distinction is critical.
My Rule
I generally only consider buying miles when all three conditions are true:
1. I Have a Specific Redemption Ready
Not a hypothetical trip.
Not a future vacation.
An actual flight available for booking.
2. The Math Clearly Works
The total cost of purchasing miles should be meaningfully lower than the cash alternative.
3. I Intend to Redeem Immediately
The shorter the holding period, the lower the risk. Ideally, I purchase the miles and redeem them the same day or within a week.
The Fare Theory
Airlines love selling miles because it generates immediate revenue.
Travelers love buying miles because it feels like they're purchasing future travel at a discount. But in most cases, that's not what's happening.
You're purchasing a currency that can be devalued, restricted, or repriced at any time.
That doesn't mean buying miles is always wrong…it means buying miles without a plan usually is. The best use of airline miles is not accumulating them.
It's redeeming them.
Because miles sitting in an account aren't creating memories. They're simply waiting for the next devaluation.
And that's exactly what The Fare Theory is about.