Boeing opted for a clean-sheet design for the 777 but stuck to a twin-engine configuration. The main reasons for this were the recent 757 and 767 models' success, lower cost for engine development, and an overall lower program price tag.

The Boeing 777, often called the "Triple Seven," is a twin-engine aircraft, meaning it has exactly two engines. In fact, it holds the record as the world's largest twin-engine jet. When it was first designed in the early 1990s, Boeing opted for a two-engine configuration to bridge the gap between the twin-engine 767 and the four-engine 747 "Jumbo Jet." The engines used on the 777 are among the most powerful in aviation history; the General Electric GE90-115B, used on the 777-300ER, was for many years the most powerful jet engine in the world, only recently surpassed by the GE9X designed for the upcoming 777X. Having only two engines makes the aircraft significantly more fuel-efficient and cheaper to maintain than four-engine competitors like the Airbus A340 or the Boeing 747. In 2026, the 777 remains the workhorse of long-haul travel, proving that two massive, highly reliable engines are more than enough to safely ferry hundreds of passengers across the world's largest oceans under ETOPS (Extended-range Twin-engine Operational Performance Standards) regulations.