8 t17,600 lb
In truck mode, Optimus Prime weighs about 8 tonnes (17,600 lb), the weight of the Peterbilt 379 tractor he turns into in the 2007 film. That is our estimate from the real truck. The only stated figure for the robot, 4.3 tonnes on a 2007 promotional trading card, is barely half of what the truck weighs.
| Peterbilt 379 sleeper with 150 gallons of dieselOur estimate: the empty truck plus about 475 kg of fuel | 8.35 t18,400 lb |
|---|---|
| Peterbilt 379 sleeper, emptyA 1992 tandem-axle truck, 17,350 lb tare as reported by its owner | 7.87 t17,400 lb |
| The 2007 film robot, promo trading card“4.3 metric tons” on a card given away with the Boston Globe | 4.3 t9,480 lb |
In Transformers (2007) and its two sequels, Optimus scans and copies a Peterbilt 379, the long-nose American tractor Peterbilt built from 1987 to 2007. The studio never gave his truck mode a weight, so we use the real truck’s. One of the actual film trucks, a 1992 Peterbilt 379 stunt truck used across the first three films, was sold at Barrett-Jackson in Scottsdale in January 2016.
A tandem-axle 379 with a sleeper cab weighs around 17,350 lb (7.9 tonnes) empty, the tare weight one owner reports for a 1992 truck with no fuel aboard. Fill a typical 150 gallons of tanks and you add roughly 475 kg of diesel, for about 8.35 tonnes. Engine, sleeper size and options move the number by a tonne or so either way, so we round to 8 tonnes.
The only weight ever printed for movie Optimus comes from free trading cards handed out with the Boston Globe in 2007. His card lists him at 28 ft (8.5 m) tall and 4.3 metric tons, about 9,500 lb. TFWiki, the main Transformers fan wiki, calls the weight implausible for his size and notes it is roughly half the weight of the truck he copies.
A quick check backs that up. Scale an 80 kg, 1.8 m person up to 8.5 m and the weight rises with the cube of the height, about 106 times, to roughly 8.5 tonnes. A solid metal robot that size would be heavier still, so the truck’s 8 tonnes is a much better fit than 4.3.
Height is not settled either. ILM’s production notes on his scale found that the truck parts on his body only match a real Peterbilt 379 if he stands about 35 ft tall, so the official 28 ft leaves him a little small for his truck.
The 1980s cartoon Optimus is a flat-nosed cab-over, most likely based on a Freightliner. The live-action films switched to the long-nose Peterbilt 379 for Transformers, Revenge of the Fallen and Dark of the Moon, which added a transforming trailer. In Age of Extinction he first hides as a rusty 1977 Marmon cab-over, then takes the form of a 2014 Western Star 5700 XE, which he keeps in The Last Knight.
Bumblebee (2018) and Rise of the Beasts (2023) go back to his roots with a red 1987 Freightliner FLA cab-over. None of these films or their makers have published a weight for him in any of these forms.
Not really. The only printed figure is 4.3 metric tons, from a promotional trading card for the 2007 film. Hasbro’s original toy bios give no weight at all.
In the 2007 film he is officially 28 ft (8.5 m) tall. ILM’s own scale notes suggest about 35 ft would be needed for his body to match the size of a real Peterbilt 379.
A Peterbilt 379 in the first three live-action films, a Western Star 5700 XE in Age of Extinction and The Last Knight, and a 1987 Freightliner FLA cab-over in Bumblebee and Rise of the Beasts. The cartoon version is a Freightliner-style cab-over.
A tandem-axle 379 tractor with a sleeper weighs about 17,350 lb (7.9 tonnes) empty and about 18,400 lb (8.35 tonnes) with 150 gallons of diesel, give or take a tonne for different engines and options. That is without a trailer.
Last checked October 2, 2026.
