For all models sold beginning with the Boeing 707 in 1957, except the 720, Boeing’s naming system for commercial airliners has taken the form of 7X7 (X representing a number). All model designations from 707 through 787 have been assigned, leaving 797 as the only 7X7 model name not assigned to a product.

For models 707 to 777, the full model number consists of an airplane’s model number, for example, 707 or 747, followed by a hyphen and three digits that represent the series within the model, for example, 707-320 or 747-400. In aviation circles, a more specific model designation is sometimes used where the last two digits of the series designator are replaced by the two digits, alpha-numeric Boeing customer code, for example, 747-121, representing a 747-100 originally ordered by Pan American World Airways (Boeing customer code 21) or 737-7H4, representing a 737-700 originally ordered by Southwest Airlines (Boeing customer code H4). Codes do not change for aircraft transferred from one airline to another. Unlike other models, the 787 uses a single digit to designate the series, for example, 787-8. This convention was followed in the development of the newest version of the 747, the 747-8, along with the 737 MAX and 777X series.