How frequent flyer programs work now
Most large airline programs now pay you for how much you spend, not how far you fly, and price awards by demand rather than by a published chart. Miles are a currency with a floating exchange rate.
Earning is based on price, not distance
The old deal was simple: fly a mile, earn a mile. The big US programs replaced it with miles per dollar spent, so a cheap transcontinental flight now earns less than an expensive short hop. Partner airlines within an alliance often still credit by distance, which is why crediting a flight to a different program in the same alliance sometimes earns more.
Before a long or expensive trip, check what each alliance partner would credit. It is a two-minute check on a calculator site and it occasionally doubles what you earn.
Awards are priced like fares
Published award charts, where a flight to Europe always cost a fixed number of miles, have mostly gone. Award prices now move with demand in the same way cash prices do, which means the same seat can cost wildly different amounts on two consecutive days.
A few programs still publish a chart or price by distance band. Those are worth knowing about precisely because they are predictable, and predictability is what makes a plan possible.
Status is bought with spending
Elite status now generally requires hitting a spending threshold, sometimes achievable through a co-branded credit card as well as flying. The benefits that matter in practice are the free checked bag, earlier boarding, and being near the front of the queue when a flight cancels. Upgrades are the thing people chase and the thing they get least often.
If you fly a handful of times a year, status is not worth reorganising your travel around. The bag fee and the boarding group are usually cheaper to simply buy.
Do not let them expire
Expiry rules vary and they change. Several large programs no longer expire miles at all; others wipe them after a fixed period with no activity. Any qualifying activity usually resets the clock, and that can be as small as a shopping portal purchase, so the fix is trivial once you know the rule.
Check your own program's current terms rather than trusting an article, including this one. This is the part of the deal airlines change most often.
Common questions
Do airline miles expire?
It depends on the program. Some never expire, others expire after a period with no account activity, usually 18 to 24 months. Almost any earning activity resets the clock.
Is it better to earn miles on the airline or on a credit card?
Transferable card points are more flexible, because you choose the airline later. Airline miles lock you into one program and one set of partners.
How much is an airline mile worth?
Roughly one to one and a half cents in typical use. Premium cabin redemptions can be worth much more, and most everyday redemptions are worth less.