Why Crediting Flights to Partners Can Earn You More Miles

When booking a flight, the most obvious choice for earning miles is to credit the flight to the airline you are flying. If you fly United, you enter your United MileagePlus number. However, this is often a missed opportunity to maximize your points. Because of airline alliances and partnerships, you can usually credit that same flight to a partner airline's program—and sometimes, you can earn significantly more.

Revenue-Based vs. Distance-Based Earning

The primary reason this strategy works is the difference in how frequent flyer programs calculate earned miles.

1. Revenue-Based Programs: Most major U.S. carriers (like United, Delta, and American) have moved to revenue-based earning. This means you earn miles based on the price of your ticket, regardless of how far you fly. If you buy a cheap ticket, you earn very few miles, even if you are flying halfway across the world.
2. Distance-Based Programs: Many international partner programs still award miles based on the physical distance flown, multiplied by a percentage dictated by your "fare class" (the letter code associated with your ticket, like 'K', 'L', or 'Y').

When you buy a cheap ticket for a long flight, a distance-based partner program will almost always be more lucrative than the revenue-based program of the airline you are actually flying.

A Real-World Example: United Airlines vs. Air Canada Aeroplan

Let's look at a common scenario to illustrate the massive difference this can make. Imagine you purchase a cheap, long-haul economy ticket on United Airlines flying from San Francisco (SFO) to Singapore (SIN).

• The Route: SFO to SIN is approximately 8,440 miles each way (16,880 miles round trip).
• The Cost: You found a great deal for $800 round trip (with a base fare of around $700).
• The Fare Class: This cheap ticket books into United's 'K' fare class.

Here is how your earnings compare depending on which frequent flyer number you attach to the reservation:

Option A: Crediting to United MileagePlus

United MileagePlus is revenue-based. As a general member, you earn 5 miles per dollar spent on the base fare (excluding taxes and fees).

• $700 base fare x 5 miles/$ = 3,500 United Miles

Option B: Crediting to Air Canada Aeroplan

Air Canada is a Star Alliance partner of United, and Aeroplan is largely distance-based for partner flights. If we check Aeroplan's earning chart for United flights, a 'K' fare class earns 50% of the distance flown.

• 16,880 miles flown x 50% earning rate = 8,440 Aeroplan Points

The Result

By simply entering your Air Canada Aeroplan number instead of your United MileagePlus number during check-in, you earn more than double the points for the exact same flight. Those 8,440 Aeroplan points are highly valuable and can be combined with points transferred from credit cards like Chase Ultimate Rewards or Amex Membership Rewards for future award bookings.

How to Find Your Best Option

To use this strategy effectively, you need two pieces of information:

1. Your Fare Class: Look for a single letter on your receipt or booking confirmation (e.g., Y, B, M, K, L).
2. The Earning Rates: Use the Flight Creditor tool above to input your airline, route, and fare class. It will automatically calculate and compare the exact miles you would earn across all eligible partner programs, taking both distance-based and revenue-based models into account.

Always check the math before you fly. A few clicks could mean thousands of extra miles toward your next vacation.