|This page uses content from Teletraan I: The Transformers Wiki. The original article was at Scale.
Scale in Transformers is, not to put too fine a point on it, screwed.
Virtually no era, franchise, fiction, toyline or other incarnation of Transformers has presented scale in a logical or believable fashion. Most fans agree that one must either ignore it or accept it, lest they be tempted to explain these problems and in the process fanwank themselves into oblivion.
However, the scale problems of Transformers still merit description.
Scale within toylines
Toys out of scale with others in the same line
The early Generation 1 toyline, especially the pre-movie lines, were repackaged and redecoed toys from several different Japanese toylines. The crucial point is that the toylines were initially unrelated. The characters should be in scale to each other as they all have real-world altmodes that (should) pass for real vehicles. However, since Diaclone toys were not part of the same line as Microman toys, scale issues arose. Diaclone figures such as Optimus Prime, Prowl and Hound are more-or-less in correct scale to each other (though problems already arise with Sunstreaker and Sideswipe, whose alternate modes are based on the same car yet are not quite the same size), but many of the Mini Vehicles from the New Microman line are clearly far too small by comparison. Even aside from their deformed penny-racer proportions, a Porsche 924 Microman toy is disproportionately tiny when compared to a Porsche 935 Diaclone toy. The disparity becomes even more obvious with Minibots such as Warpath (a tank) and Seaspray (a hovercraft), who should be many times their actual size.
Another glaring scale problem comes in the form of the Seekers, who turn into F-15 Eagles which, in real life, are 19.4 m (63.8 feet) long. Correctly scaled, this would make their robot modes colossal compared to most Autobots. Similarly, the Constructicons, despite also coming from the Diaclone line, are too small.
Toys out of scale within teams
Even toys specifically designed to interact with each other suffer from this problem. The Combaticons are wildly out of scale to each other — Blast Off's space shuttle mode should dwarf Swindle, with the others somewhere in between. Instead, they're about the same size. Among the Constructicons, Long Haul is designed to look like a gigantic "earth-mover" mining truck. He should be able to carry all his teammates in his bed, with some crowding. Similarly, Silverbolt (a Concorde jet) is dramatically undersized compared to his fighter-jet Aerialbot teammates. These scale problems are necessary to avoid misproportioned gestalt forms.
Same altmode, different sizes
Other scale problems come from characters who transform into the same (or similar) altmodes but whose toys are different sizes. For example Air Raid transforms into an F-15 Eagle, but his toy is half the size of Starscream's. The same can be said for the Lamborghini Countach Breakdown, who should be the same size as Sunstreaker and Sideswipe, not significantly smaller. These discrepancies are also seen in the other Scramble City combiners with Earth altmodes, whose toys are all smaller than similar earlier toys.
On the MUX we try to have it both ways. Through a combination of contraction and mass-displacement, most Transformers on the MUX have the robot sizes consistent with known fiction (Mini-bots are smaller than "regular" Transformers), but their vehicle sizes are the same sizes as their real-world counterparts (in vehicle mode Breakdown and Sideswipe are the same size, as are Air Raid and Starscream). There are slight changes made to robot modes for the largest discrepancies - Swindle is a size smaller than the other Combaticons, and Blast Off a size bigger - but overall we try to stick to familiar proportions for robot modes (Leaders are bigger even with smaller altmodes, etc.)