Compared to the 737 Classic, it has a redesigned wing with a larger area, a wider wingspan, greater fuel capacity, and higher maximum takeoff weights (MTOW) and longer range.

It has CFM International CFM56-7 series engines, a glass cockpit, and upgraded and redesigned interior configurations.

The smallest of the new variants, the −600 series, is identical in size to the −500, launching in December 1997 with an initial flight occurring January 22, 1998; it was granted FAA certification on August 18, 1998.

[7] In 2004, Boeing offered a Short Field Performance package in response to the needs of Gol Transportes Aéreos, which frequently operates from restricted airports.

[9] Delta Air Lines received the first Next-Gen 737 model with this brake package, a 737-700, at the end of July 2008.

[10] The CFM56-7B Evolution nacelle began testing in August 2009 to be used on the new 737 PIP (Performance Improvement Package) due to enter service mid-2011.

[13] In 2005, three ex-Boeing employees filed a lawsuit on behalf of the U.S. government, claiming that dozens of 737NG contained defective structural elements supplied by airframe manufacturer Ducommun, allegations denied by Boeing.

[14][15] The federal judge presiding the case sided with Boeing, and a subsequent court of appeal also ruled in favor of the company.

[17] However, the accident investigations in all three cases did not highlight any link between post-impact structural failures and manufacturing issues.

Boeing reported the issue to the FAA at the end of September 2019, and more planes showed similar cracking after inspection.

[23] Following the contained engine failure of the Southwest Airlines Flight 1380 on April 17, 2018, the National Transportation Safety Board (NTSB) recommended on November 19, 2019, to redesign and retrofit its nacelle for the 6,800 airplanes in service.

The final assembly process begins on Day 6 with the installation of airline seats, galleys, lavatories, overhead bins, etc.

The last aircraft assembled was a 737-800 registered PH-BCL delivered to KLM in December 2019; the last two deliveries were to China Eastern Airlines on January 5, 2020.

[2] The FAA has proposed a fine of approximately $3.9 million for Boeing's alleged installation of the same faulty components of the 737 MAX on some 133 737 NGs.

[32] In 2011, Boeing launched the 737 MAX, an updated and re-engined version of the 737NG with more efficient CFM International LEAP-1B engines, and aerodynamic changes with distinctive split-tip winglets.

[40] The Speed Trim System, introduced on the 737 Classic, has been updated for the 737NG to include a stall identification function.

[41] The flight deck was upgraded with modern avionics, and passenger cabin improvements similar to those on the Boeing 777, including more curved surfaces and larger overhead bins than previous-generation 737s.

[11] It introduced new pivoting overhead bins (a first for a Boeing narrow-body aircraft), new sidewalls, new passenger service units, and LED mood lighting.

When outfitted with nine auxiliary fuel tanks, it can hold 10,707 US gallons (40,530 L; 8,915 imp gal) of fuel with a 171,000-pound (78,000 kg) MTOW, but with a cargo payload capacity significantly decreased from 966 to 165 cu ft (27.4 to 4.7 m3), trading payload for increased range of 5,775 nmi (10,695 km; 6,646 mi).

[55] In 2011, United Airlines— flying a Boeing 737-800 from Houston to Chicago—operated the first U.S. commercial flight powered by a blend of algae-derived biofuel and traditional jet fuel to reduce its carbon footprint.

[59] Ryanair, an Irish low-cost airline, is among the largest operators of the Boeing 737-800, with a fleet of over 400 of the -800 variant serving routes across Europe, Middle East, and North Africa.

Boeing started the program with orders for 55 conversions, with the first converted aircraft due for late 2017 delivery.

[63] Since early 737NG aircraft become available on the market, they have been actively marketed to be converted to cargo planes via the Boeing Converted Freighter design because the operational economics are attractive due to the low operating costs and availability of certified pilots on a robust airframe.

[1] The 737-900ER (Extended Range), which was called the 737-900X before launch, was the final and largest variant of the Boeing 737 NG line.

[73] It was introduced to fill the range and passenger capacity gap in Boeing's product offerings after the 757-200 was discontinued, address the shortcomings of the 737-900, and to directly compete with the Airbus A321.

Up to two auxiliary fuel tanks in the cargo hold and standard winglets improved the range of the stretched jet to that of other 737NG variants, while an additional pair of exit doors and a flat rear pressure bulkhead increased maximum seating capacity to 220 passengers.

[74][75][73] Airlines may deactivate (plug) the additional exit doors if the total configured capacity of the plane is 189 passengers or less.

[76] The first plane was delivered to its launch customer, the Indonesian low-cost airline Lion Air, on April 27, 2007, and was painted in a special dual paint scheme combining Lion Air's logo on the vertical stabilizer and Boeing's livery colors on the fuselage.

The BBJ (retroactively referred to as the BBJ1) was similar in dimensions to the 737-700 but had additional features, including stronger wings and landing gear from the 737-800, and has increased range (through the use of extra fuel tanks) over the other various 737 models.

[87] The deadliest occurrence for a 737NG is Jeju Air Flight 2216, a 737-800, which overshot the runway while performing a belly landing at Muan International Airport in South Korea and crashed into an embankment on December 29, 2024, killing 179 of the 181 on board.