As it is a twinjet, the aircraft is more economical to operate than some larger quadjets, like the Airbus A380 or the Boeing 747. The 777-300ER, despite being powered by only two engines, does not necessarily sacrifice capacity. Air Canada, for example, fits as many as 450 passengers onboard some of its 777-300ERs.

The Boeing 777-300ER (Extended Range) is incredibly popular among airlines primarily because of its efficiency, reliability, and immense capacity. Often called the "Big Twin," it was designed to replace older, fuel-hungry four-engine aircraft like the Boeing 747. It offers nearly the same passenger capacity but with significantly lower fuel consumption and maintenance costs thanks to its two massive GE90-115B engines—the most powerful jet engines in the world for many years. With a range of over 7,300 nautical miles, it allows airlines to fly "long-and-thin" or high-demand transoceanic routes profitably. Additionally, the aircraft is a favorite for passengers due to its spacious "Signature Interior," which features wider cabins and pivoting overhead bins. Its exceptional 99.5% schedule reliability means it is on time almost all the time. By 2026, even with the introduction of the 777X, the -300ER remains the backbone of long-haul fleets for major carriers like Emirates, Air France, and United because it perfectly balances cargo-carrying capability with passenger comfort.