Boeing 737 1st Gen vs Classic Series – What Are The Differences?

It was the late 1960s when the very first generation of Boeing 737s entered commercial service. On December 28th, 1967, Lufthansa took delivery of the first production 737-100. The following day, United Airlines, took delivery of the slightly longer 737-200. Nearly two decades later, the 737 “classic series” would continue the legacy of Boeing’s famous new single-aisle jet. The  737-300 and -400 flew for the first time in February 1984, with deliveries taking place later that year. So, how much changed between the very first series of 737s and Boeing’s first round of updates? Let’s take a look and find out.

Nolinor is one of the few carriers in the world still operating the 737-200. One main reason is for its gravel landing abilities. Photo: Nolinor

To make things clear, we’ll be referring to the -100 and -200 variants of the Boeing 737 as the first generation. When we refer to the Classic series, we’re talking about the -300, -400, and -500.

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Sizing and dimensions

The wingspan between the two series differs slightly, with the first generation’s stretching 93 feet (28.34 meters) compared to the Classic’s 94.9 feet (28.93 meters).

In terms of length, the -100 was a stubby 93 feet and 9 inches (28.58 meters) while its longer -200 variant was just over 100 feet long (30.53 meters). Boeing must have realized the potential of its new airframe in carrying more passengers.

ANA wings 737-500
Although roughly half a meter longer than the -200, the 737-500 was actually the shortest of the 737 Classic series. Photo: G B_NZ via Wikimedia Commons

The Classic series received a significant boost in overall length with the shortest -300 variant stretching 109 feet and 7 inches (33.4 meters). The -400 gets an additional 10 feet (3 meters). Going against popular naming convention, the -500 was actually shorter than its -300 and -400 siblings. This later Classic variant stretched just 31 meters – 101 feet and 9 inches.


Naturally, differing dimensions will result in differing capacities. It’s clear with the length dimensions presented that the Classic series offers more capacity across the board – even with the shortest -500 variant – which is about half a meter longer than the 737-200.

The first generation could seat around 124 passengers in a typical high-density setup, while the capacities for the -500, -300, and -400 were 132, 149, and 168, respectively. Thus, the longest Classic offered as many as 35% more seats than the first generation.

Boeing 737 1st Gen vs Classic Series  – What Are The Differences?
The 737-400 is the longest variant in the Classic series. Photo: First Air


The first generation of 737s were powered by two Pratt & Whitney JT8D engines. The -100 was equipped with the JT8D-7, which could provide 14,000-pound-thrust (lbf) while the -17 could do 16,000 lbf. Different sources have different numbers, but according to Skybrary, this gave the -100 a range of about 1,500 nautical miles (2,778 kilometers) and 1,200 nautical miles (2,222 kilometers) on the -200.

As for the Classics, the three models were all powered by the CFM56-3C-1. These could provide as much as 23,500 lbf, a near 47% increase in power compared to the first generation. The -500 could fly about 1,400 nautical miles (2,592 kilometers), while the -300 had a design range of 1,635 nautical miles. The -400’s design range was just over 1,900 nautical miles.

Lufthansa 737
A look at Lufthansa’s 737-100 on the ground with its slim and small engines. Photo: Lars Söderström via Wikimedia Commons 

The engine change between the two series led to a big change in appearance. The first generation’s small, slim engines were referred to as ‘cigar tubes’ while the Classic series had larger, flat-bottomed engines – sometimes referred to as ‘hamster pouches.’ The shape allowed the Classic series to maintain a low height from the ground, which mitigated the need for cargo handling equipment, as noted by Boeing in promotional material.

Variants and their abilities

Finally, it could be noted that the first general had a gravel kit available to it, which allowed for the early 737s to land on unpaved runways safely. This was not made available first subsequent series of 737s.

On the other hand, the 737 Classics had a combi variant that allowed for a mix of large cargo as well as passengers.

Boeing 737 1st Gen vs Classic Series  – What Are The Differences?
The 737-400 Combis were a core part of Alaska Airlines’ operations. Photo: Alaska Airlines

Indeed, we could say a lot more about the differences between various 737 models as technological advancements have changed a lot about this aircraft in its early years.

The 737 would go on to evolve twice more, with the Next-Generation series following the Classic, and the MAX series after that.