What Are Airline Miles?

Airline miles are the currency of a frequent flyer program. You earn them by flying, by spending on partner credit cards, and by transferring points from a bank, and you spend them on flights, upgrades, and other rewards.

In the early programs a mile flown earned a mile in the account, so the currency was named for distance. Today most miles are earned on the ground, most programs award them based on what you paid rather than how far you went, and several programs call them points instead. The sooner you stop thinking of the unit as distance, the better your decisions get. This post explains what miles are, what they are worth, and how to hold them without losing them. Rules are current as of September 2026. If you want the program side first, start with what a frequent flyer program is.

Miles, Points, and the Difference That Matters

Three kinds of currency get called "points", and only one of them is airline miles.

• Airline miles live in one airline's program: AAdvantage miles, MileagePlus miles, Flying Blue miles, Avios. Each is its own currency, spendable within that program and on its partners, and not convertible back into anything else.
• Bank points live in a credit card program: American Express Membership Rewards, Chase Ultimate Rewards, Citi ThankYou, Capital One miles, Bilt, Wells Fargo. These are flexible: they transfer into many airline and hotel programs, usually at one to one, and until you transfer them they are not committed to any airline.
• Hotel points live in Marriott, Hilton, Hyatt, or IHG. They can be spent on rooms or, at poor rates, transferred to airlines.

The practical rule that falls out of this: airline miles are for spending, bank points are for holding. A balance in a bank program can be sent to whichever airline has the cheapest seat on the day you need one. A balance in an airline program can only be spent there.

The Five Ways to Earn Miles

• Flying. Book a paid ticket, add your program number, and the miles post after the flight. At most large carriers you earn a multiple of the fare paid, five to eleven miles per dollar depending on status. At many international programs you still earn by distance flown, adjusted by fare class, where a deep-discount fare might earn a quarter of the miles a full fare does. You can credit a flight to any program the operating airline partners with, not only the airline's own.
• Credit cards. A co-brand card earns miles in one airline's program on every purchase, and its signup bonus is often the fastest way to a business class seat. A bank card earns flexible points instead.
• Transfers from bank points. For most travelers this is where the big balances come from. A bank's points move into an airline program in minutes, and the banks run transfer bonuses of 20 to 40 percent several times a year.
• Partners. Hotel stays, car rentals, online shopping portals, dining programs, and a growing list of everyday retailers.
• Buying. Every program sells miles. The price is usually higher than the miles are worth, with occasional exceptions when a sale price beats the cash fare of a specific seat you have already found. Our post on points arbitrage covers when that math works.

What a Mile Is Worth

There is no fixed answer. A mile is worth what it buys, and the range is enormous. Typical value per mile by how you spend it:

• Merchandise, gift cards, magazines: about half a cent to seven-tenths of a cent.
• Hotels and cars through an airline portal: around a cent or less.
• Economy flights on cheap routes: one to one and a half cents.
• Economy on expensive dates, or short flights with low fixed prices: around two cents.
• Long-haul business and first class: three to six cents, sometimes more.

The formula, for any specific redemption: take the cash fare you would actually pay, subtract the taxes and fees charged on the award, and divide by the miles. A business class seat that costs $3,800 in cash, or 60,000 miles plus $150, returns about six cents per mile. A $300 domestic ticket for 25,000 miles plus $6 returns barely more than a cent. Two consequences follow. A balance has no single dollar value until you decide how to spend it, which is why "I have $1,000 in miles" is never quite true. And the way to make miles worth more is not to earn more of them but to spend them on the seats where cash is most expensive, which we go into in how to use your airline miles most effectively.

How You Spend Miles

• Award flights are the main use. Each program sells seats on its own flights and on its partners' flights for miles plus government taxes and, at some airlines, a carrier surcharge. The cheapest tier, usually called saver or partner space, is released in limited numbers. Pricier tiers exist on the airline's own flights when saver space is gone.
• Upgrades let you move a cash ticket up one cabin for miles, sometimes with a cash co-pay. The fare you bought has to be eligible, basic economy never is, and upgrade space has to exist, which is a separate question from award space.
• Everything else is generally a poor use of the currency.

Are All Miles the Same?

No. Every program's miles are a separate currency with a separate price list, and the price of the same seat differs from one program to the next. A Lufthansa business class seat across the Atlantic costs 80,000 to 88,000 United miles with no surcharges, or roughly the same in Lufthansa's own Miles & More miles plus about €1,150 in surcharges. A Qatar Qsuite seat costs about 70,000 miles through American, Qatar Privilege Club, or Atmos Rewards, but adds around $235 in surcharges through British Airways.

Some programs share a currency. Avios is the shared currency of British Airways, Iberia, Qatar, Finnair, and Aer Lingus, and you can move it between your own accounts at those programs free and instantly. That lets you earn Avios anywhere and spend them through whichever of the five prices your route cheapest. Otherwise, miles do not move between airlines. Once transferred into a program, they stay there.

Do Miles Expire?

Some do, and the rules differ enough that it is worth knowing yours. As of September 2026:

• Never expire while the account is open: United, Delta, Atmos Rewards (Alaska and Hawaiian), Virgin Atlantic.
• Expire after inactivity, and any earn or redeem resets the clock: American after 24 months, with under-21s and cardholders exempt. Aeroplan after 18 months. Cathay's Asia Miles after 18 months. Flying Blue on a single rolling 24-month clock since May 2026, with elites, co-brand cardholders, and under-18s exempt. Avios after 36 months at British Airways, Iberia, Qatar, and Aer Lingus, but only 18 months at Finnair.
• Expire on a hard clock regardless of activity: ANA, 36 months from earning, at month end, with no extension. Miles & More, 36 months per mile unless you hold status or a qualifying card.

The cheapest way to keep an inactivity clock alive is usually a tiny earn, such as a shopping portal purchase or a small transfer. Hard clocks cannot be extended, so plan the redemption before the cliff.

Can You Buy, Sell, or Give Miles?

• Buying from the program is allowed and rarely worth it, except when a sale price beats the cash fare for a specific seat you have already confirmed.
• Transferring from a bank is the normal way to add miles, and it is irreversible. Confirm the seat exists before you move points.
• Giving miles to another person is restricted. Some programs let members pool balances within limits: United's Miles Pooling takes up to five members, Flying Blue Family up to eight, British Airways household accounts up to six at one address. Others restrict who can fly on your miles: ANA awards are only for the member and relatives within two degrees, and Cathay awards only for the member and registered nominees.
• Selling miles, or buying an award ticket that someone booked from their own account, breaks every program's rules. Airlines audit for it and close accounts, and the ticket can be cancelled at the airport. Book awards from your own balance or through legitimate pooling.

The Taxes and Fees on an Award Ticket

"Free flight" is a phrase to retire. Every award carries government taxes and airport fees, from about $6 on a US domestic one-way to a few hundred dollars on an international itinerary. Some airlines add a carrier surcharge on top, which can run from a couple of hundred to more than a thousand dollars in premium cabins. British Airways, Lufthansa, ANA, Cathay, and Virgin Atlantic are the usual culprits. United, Aeroplan, American on most partners, and Atmos on most partners charge none.

Whether the fee is worth paying comes back to the cents-per-mile calculation. A $1,150 surcharge on a seat that costs $4,500 in cash may still be a fine deal. It is just not free.

Common Misconceptions

• "I earned 5,000 miles, so I can fly 5,000 miles." The name is historical. The miles in your account have no relationship to distance.
• "Miles are free money." They are a currency you earned by spending, worth between half a cent and several cents each depending on how you use them.
• "I should credit the flight to the airline I'm flying." You can credit it to any partner program, and a different program may earn more or expire later.
• "I should transfer my bank points now so they're ready." Transfers are irreversible. Keep bank points flexible until you have a seat in hand.
• "The award price I see is the award price." The same seat is usually for sale through several programs at several prices. Check the partners before you book.
• "Award seats are always available if I have enough miles." The cheapest seats are released in limited numbers and in waves, roughly 11 months out and again in the last two weeks. Flexibility and alerts matter more than the size of the balance.

Frequently Asked Questions

• How many miles do I need for a business class ticket? It varies by route and program. As of September 2026, a one-way business class seat between the US and Europe runs from about 40,500 miles on Iberia off-peak through Avios, to 57,500 through American on Finnair, Iberia, or American, to 80,000 to 88,000 through United on Lufthansa and other Star Alliance carriers. To Japan, JAL business is 60,000 American miles on a nonstop and ANA is 52,500 to 60,000 Virgin Atlantic points.
• Can I combine miles from two programs for one ticket? Not on a single ticket. You can book the outbound with one program and the return with another, since most programs now sell one-ways at half the round-trip price.
• What happens to my miles if the airline changes its program? Balances usually convert. Alaska and Hawaiian members' balances merged one to one into Atmos Rewards in October 2025. What changes is the price list, so a devaluation can shrink what a balance buys without touching the number.
• Are miles taxable? In the US, miles earned from spending are generally treated as a rebate and not taxed. Miles received as a bonus without a purchase can be treated as income. Ask a tax adviser about your situation.

Values, rules, and prices in this post were verified in September 2026 and will change. Confirm the current figure with the program before you book.