6 Things You Need to Know About Airline Miles

By Michael Stratford

1. Pick the right program. Before you sign up, assess your flying habits. If you fly frequently, you want a relationship with the airline that offers you the most convenient flights. Generally, it’s best to pick the largest carrier at your hometown airport. If you’re not sure which one it is, check the airport’s Web site to find the airline that occupies the largest number of gates. If you rarely fly, you might want to opt for a rewards card instead. These cards tend to offer lower rates, let you choose the airline and don’t have blackout dates.

2. Put all your eggs in one basket. Diversification is a good investment strategy, but it’s not a sound practice for frequent-flier miles. Because the miles or points you earn in one program usually can’t be exchanged or transferred to others, it often makes sense to participate in just one program. That way, you earn the most usable miles and avoid small balances spread over multiple accounts. It typically takes about 25,000 miles to redeem a flight within the continental U.S.

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3. Bag the miles and buy the ticket. Despite your affinity for one airline, if you can find a cheaper flight on another, take it. (Use sites such as Kayak.com and Airfarewatchdog.com to compare prices.) “It rarely ever makes sense to overpay to earn extra miles,” says Tim Winship, publisher of FrequentFlier.com. Pay extra only if the miles you earn on the more expensive flight cost less than their redeemable value (a frequent-flier mile is worth, on average, 1.2 cents). Plus, you may still be eligible to earn miles in your program through partner airlines.

4. Keep your miles alive. Every program has its rules, but miles typically start to expire if your account has been inactive for 18 to 24 months. You can, however, reset the clock. “Earning a mile or burning a mile usually gives you another 18 months,” says Winship. Aside from booking a flight, the easiest way to ensure that you hold on to your miles is to sign up for an airline credit card that’s tied to your program and use it.

5. Rack up miles on the ground. You should also be aware of each airline’s rewards-program partner companies. The largest programs—those sponsored by Delta, United and American—list thousands of partners on their Web sites, including retailers and hotel chains. Also take advantage of your program’s “mileage mall,” a network of online retailers that offer reward miles, and use your program-affiliated credit card to make purchases at these stores.

6. Know when to fold ’em. Business passengers are usually interested in turning their miles into in-flight perks and upgrades. Casual fliers are all about free flights. Because airlines have started filling their planes to capacity, the supply of rewards seats is more limited. But it’s still possible to snag a free flight, especially if you book ahead (as many as 330 days prior to departure) or late (two weeks before). Look for midweek flights during off-peak periods, and avoid weekends and holidays. Another strategy is to fly from or to a nearby airport. Airlines are encouraging participants to redeem miles for rental cars, free hotel stays and consumer electronics. But before you take them up on the offer, do the math: Nonflight rewards usually offer a lower return on your investment.