How Heavy was the T-Rex

We all know that the T-Rex was the King of the Dinosaurs. It’s literally in the name it may be the most famous, most well known and most popular but it likely wasn’t actually the biggest carnivore out there. We take a look at if not the longest or biggest, was it the most heavy of the carnivorous dinosaur when we take a look at how heavy was a T-Rex in the article below.

The T-Rex was one of the largest and most heavy of all species of carnivorous dinosaurs. Fossil examinations have estimated that a Fully Mature T-Rex could weigh between 16,500 pounds and 19,500 pounds. (7000 – 9000 kg) This weight makes it one of ,if not, the heaviest land carnivorous dinosaurs of all time.

Although we have never, and hopefully will never see one up close and personal, the T-Rex looks like a pretty awesome creature. Even by looking at their bones in museums, we can tell that they, and all other dinosaurs were one of the most magnificent animals to ever live, and while they were certainly huge, were they actually heavy as well?

how heavy was the t rex

That’s what we are taking a look at in the article below, how heavy exactly was the T-Rex? We will be going through the evidence of exactly how heavy scientists believe this incredible giant dinosaur was when it was stomping around 66 million years ago.

We have a T-Rex infographic with the weight, height, length and more facts about T-Rex for you to share and use. Just drop us a credit if you do 🙂

T Rex Facts infographic

What we know about the T-Rex: a literal heavyweight

As the world’s most popular and famous, upright, terrifying and carnivorous theropod, we love learning all there is to know about them.

Some facts we have learned about the T-Rex include:

  • It lived 66-70 million years ago.
  • It was a carnivore, therefore ate other dinosaurs.
  • The average lifespan of a T-Rex was possibly 30 years.
  • It was 12 meters/40 feet in length.
  • It was 3.6 meters/12 feet tall.

As for the weight, scientists believe T-Rex would have weighed a minimum of 5,000 – 9,000 kilograms/11,000 – 19,000 pounds with all the bones, muscle and flesh.

But how do scientists determine this fact? It’s not like they have a T-Rex to coax onto huge weighing scales to record the weight and call it a day.

No, they did not have an actual, fully formed, T-Rex. But they do have their bones. Almost full skeletons, in fact. We take a look at how scientists estimate how heavy a T-Rex was in the next section.

How do we know the weight of a T Rex

As we mentioned it is not possible to sedate a T Rex, or any dinosaur for that matter, and put it on a super size bathroom scale, and we should be thankful for that!

Similarly weighing the fossils of the dinosaur is not much use for three important reasons.

  • 1) The bones are just that bones, they do not represent the full dinosaur with flesh, gristle, tendons teeth etc and would, even if possible to weigh them and see how heavy they are it would not be accurate.
  • 2) It is incredibly rare to find a full skeleton of any dinosaur fully fossilized, even Sue the most complete of all the T-Rex fossils discovered was 90% complete by bulk ( 250 of 360 bones)
  • 3) Thirdly, and most importantly fossils are not bones. The bones have been replaced by rock, which as you might expect is an entirely different substance and of course is much more heavy than the bone that it replaced over millions of years.

So scientists have had to develop other ways to try to accurately estimate the weight of dinosaurs. One of these ways is by using the circumference and length of animal bones and comparing it to both similar dinosaurs that may be better researched, or even modern day animals and scaling up ( usually up) to find an approximate weight and height.

This system has been in effect since around 1985, and although it is pretty accurate for smaller animals it can be wildly off the mark for larger ones. ( the example given here is when they used this method in 2009 for elephants and hippos is made them much heavier than they actually are.

The second and older way, is to reconstruct the dinosaur as accurately as possible and then “flesh it out with educated estimates of body mass and as much evidence as can be taken from the fossils and the area it was found. Now this can be much better done with computer modelling, but even so a combination of the two tends to be the best way.

The actual weight of dinosaurs would be down to many more factors than just the length and width of bones. It would come down to what and how much the dinosaur had to eat to maintain body weight, the temperature or climate it lived in, and its general build which can be hard to work out from a fossil as it rarely gives an idea of the flesh covering those bones.

how heavy was the t rex

Was T Rex the Heaviest Dinosaur

As heavy as a T-Rex was, even the heaviest scotty ( see below) was nowhere near the weight of even a medium sized sauropod. The largest dinosaur is another topic that is under constant review and debate and although it can vary on the exact species there is consensus that it would have been a sauropod, be it Argentinosaurus, a species of Barosaurus or even the mysterious vanishing dinosaurs like Amphicoelias and Bruhathkayosaurus.

We have articles on the largest ever dinosaurs, and on the missing fossils of the amphicoelias in the links bolded above. It’s worth reading as if ever found or verified it would be a dinosaur to rival even the blue whale in size!

Was T Rex it the Heaviest Carnivore Dinosaur.

Well, this is a very loaded question, and the answer unfortunately is probably. There are 4 large carnivorous dinosaurs that view for the title of largest carnivore dinosaur and its such a large question we wrote more about it in its own article “what was the largest carnivore dinosaur” which goes further to answer the question than we can here.

however, the crib note answer is of the four it is very likely that Tyrannosaurus Rex was the most bulky, most heavy and massive of the four. the other three being Spinosaurus, Giganotosaurus and Carcharodontosaurus but there are arguments for all four to take the that title and in truth despite the amount of debate and dispute over the answer all four were very close in size and weight.

Spinosaurus and Giganotosaurus were likely bigger and longer in length but the T-Rex was like the dinosaur equivalent of a Bull Dog and being made of muscle more heavy, even if a slightly ( though still of course massive) smaller frame. Even Carcharodontosaurus was a similar length ( at least one species – saharicus) and estimated to be up to 6-7 tons in weight.

We have the table below that takes the weight estimates for the big four and you can check out the full article on the link we mentioned above or take a look at the other infographic below the table which gives some details about all four of these massive predatory dinosaurs and how heavy they were.

NOTE: We took the most recent available weights from Wikipedia for continuity and weights are always debated or disputed depending on the source or methods used to calculate ( more on that above).

Table 1: Weight Comparison four heaviest carnivore dinosaurs.

When estimated and paleontologist. Largest Carnivorous DinosaursEstimated Weight maximum LbsEstimated Weight maximum Kgs
2019 Scott PearsonTyrannosaurus Rex19,5558,870
2022 – Paul SerranoSpinosaurus16,3147,400
2019 – Matías ReolidGiganotosaurus18,739.38,500
2015 – D M HendersonCarcharodontosaurus13,6686,200

We have included links to the papers where available for the most recent maximum weight estimates

and the Largest Carnivore infographic as mentioned above.

4 largest carnivore dinosaurs infographic

The Four Heaviest T Rex Fossils.

There have been around 100 T-Rex fossils discovered by palaeontologists over the years. But getting a nearly complete fossilized skeleton of a T-Rex is rare of those only 32 adults have been found that are of a reasonable level of completeness. ( many are single bones)

However, scientists have managed to put the bones of these incredible beasts together to give us a better look at their beauty and enormous size 3 of the example T Rex fossils below are some of the most complete and most heavy examples of a T-Rex and the last one is to show that at least for some of its years the T-Rex was not the 40 foot long, 19000 lbs apex predator it is usually depicted as.

how heavy is a t rex


Sue became famous as the pun-loving dinosaur of Twitter. The fossils are currently on display in the Chicago Museum to view.

No one really knows the sex of Sue the T-Rex, since it is difficult to determine gender in fossils. However, the skeleton was named after Sue Hendrickson, who discovered the bones back in the 1990s during a commercial excavation trip in South Dakota.

Sue is 40 feet long and 13 feet tall. They are also some of the the most complete T-Rex skeleton out of the entire 30+ fossils with reasonable completeness ever discovered. They have 250 of 380 known bones of the T-Rexes skeleton.

The skull alone weighs 600 pounds, with the entire body estimated to weigh around 18, 651 pounds. They may be the most complete, but they aren’t the heaviest.


Stan was found in Hell’s Creek, South Dakota, in 1987. However, they weren’t excavated until 1992. As well as sharing a US state with Sue, he is also one of the most complete T-Rex fossils in the world, with more than 70% of his bones discovered

Stan was named after Stan Sacrison, an amateur paleontologist who made the initial discovery of the T-Rex fossil. He wasn’t even looking for a T-Rex at the time. He was looking at the plant life when he noticed a pelvis bone sticking out from a cliff.

Maybe Stan and Sue were friends back in the day, they weren’t all that far from one another.

Nose to tail, Stan is about 40 feet long and was measured to be around 13 feet tall, just like Sue. Although Stan weighs 16,875 lbs, which makes Sue the heavier of the two.

Stan was auctioned for $31,847,500 on 6th October 2020 and is now housed in a new and upcoming museum in Abu Dhabi.


Scotty is literally the heavyweight champion when it comes to the T-Rex fossils that have been discovered.

Scotty was discovered in Canada in 1991 by Robert Gebhard and a team of Paleontologists on a local expedition. They simply stumbled across the fossil and it turned out to be one of the biggest Canadian finds in history.

They recovered 65-70% of Scotty’s skeleton and it is on record for being the world’s largest T-Rex ever found. At 19 feet tall and 39 feet long, they estimated the weight an incredible 19,555 pounds by measuring the circumference of the femur. This one was definitely King of the Dinosaurs.

When making the discovery, the scientists wanted to toast their incredible find. However, the only spirit on hand was a bottle of Scotch, which is why the T-Rex was named Scotty. We can at least be thankful its wasnt fanta or tea i guess!


There was a lot of back and forth about whether Jane was a T-Rex or a different species of dinosaur. This debate went on for about 70 years. That’s a long argument!

Jane was discovered in Hell Creek Formation in Montana back in 2001 by Carol Tuck and Bill Harrison, team members of an expedition led by Burpee Museum Illinois.

It was finally agreed that Jane was, in fact, a juvenile T-Rex and not a different dinosaur species. Although, one could understand the confusion.

Jane is 21.5 feet long, which is half the length of Sue, and was 7.6 feet tall. A dwarf compared to the other T-Rex on this list. The tiny thing only weighed 1,500 pounds.

It was determined that Jane was a juvenile T-Rex by scientific efforts that have progressed over the years. They are now able to narrow down the age of the fossil when it died. So, after taking another look at Jane, it was agreed that it was a T-Rex of about 11 years of age.

We have a huge selection or articles to answer the common and some less common questions about the Tyrannosaurus Rex here on the site and to make it easier to access we have them in the table below.

How heavy was T-RexDid T-Rex Ever Eat PlantsT-Rex Vs. MammothDid T-Rex have Bad Eyesight
Did T-Rex RoarHow Tall was T-rexDifferences between T-Rex and VelociraptorDid T-Rex Hunt in packs
T-Rex Vs SpinosaurusHow big was a T-Rex BrainCould T-Rex Swim?Did T-Rex have Wings
Did T-Rex Lay EggsClosest living relative to T-RexTriceratops Vs. T RexHow fast could T-Rex run
How big was a T-RexT Rex Facts

Final Thoughts

From itty-bitty Jane to the humongous Scotty, T-Rex came is all shapes and sizes, and while Tyrannosaurus Rex was like to be the heaviest predator ever to walk the Earth, (even at its average size it would have outweighed most of the others)

However all were huge carnivores of almost identical proportions, just with its added mass and muscle, and with actual fossilized Evidence with the T-Rex – Scotty – topping the chart at 19500 lbs, T rex would have been Heavy, and probably the heaviest of them all.


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