The biggest dinosaur in the Natural History Museum’s directory, Argentinosaurus, was about 35 metres (115ft) long and 70 tonnes, roughly twenty times the height of an average UK man (1.78m). T. rex was about 12 metres (39ft) long, and Velociraptor was only about 1.8 metres (6ft), turkey-sized rather than human-sized.
Dinosaur sizes compared with a person
Lengths and weights are the Natural History Museum’s Dino Directory figures. The last column divides each length by the height of an average UK man (178.21cm), to show how many “men” the animal would be end to end. Note this compares a length with a standing height, so it measures scale rather than how tall each animal stood.
| Dinosaur | Length | Weight | Length in UK-man heights |
|---|---|---|---|
| Argentinosaurus | 35m (115ft) | 70,000kg | 19.6 |
| Diplodocus | 26m (85ft) | 15,000kg | 14.6 |
| Brachiosaurus | 22m (72ft) | 46,900kg | 12.3 |
| Spinosaurus | 14m (46ft), an estimate | 7,400kg | 7.9 |
| Giganotosaurus | 13m (43ft) | 13,800kg | 7.3 |
| Tyrannosaurus | 12m (39ft) | 7,000kg | 6.7 |
| Triceratops | 9m (30ft) | 10,000kg | 5.1 |
| Stegosaurus | 9m (30ft) | not stated | 5.1 |
| Ankylosaurus | 8m (26ft) | 8,000kg | 4.5 |
| Velociraptor | 1.8m (6ft) | 7kg | 1.0 |
| Compsognathus | 0.7m (2.3ft) | 3kg | 0.4 |
How does that compare with things you know?
A cricket pitch is 22 yards, or 20.12m, and a tennis court is 23.77m long (both from the standard rules of each sport). Against those:
| Dinosaur | Length | Cricket pitches | Tennis courts |
|---|---|---|---|
| Argentinosaurus | 35m | 1.74 | 1.47 |
| Diplodocus | 26m | 1.29 | 1.09 |
| Brachiosaurus | 22m | 1.09 | 0.93 |
| Tyrannosaurus | 12m | 0.60 | 0.50 |
An Argentinosaurus laid along a cricket pitch would overshoot the far end by about 15 metres, nearly three-quarters of a pitch again. A T. rex would cover a little over half of the pitch.
| Name | Height |
|---|---|
| Compsognathus (approx. hip) | 30 cm |
| Velociraptor (approx. hip) | 50 cm |
| UK average man | 178.2 cm |
| T. rex (hip height) | 370 cm |
The small ones: Velociraptor and Compsognathus
Two entries on the list fit in a car boot. The Natural History Museum gives Velociraptor as about 1.8 metres long and about 7kg, and Compsognathus as about 0.7 metres and 3kg. A person can look down on both.
Popular film versions of Velociraptor are scaled up to the size of a person, which is why the real animal surprises people. The museum figure of 1.8m long is about the same as an average UK man’s height, but most of that length is tail. Its body was a fraction of a person’s size.
The giants: long necks versus big predators
The three largest animals in the table, Argentinosaurus, Diplodocus and Brachiosaurus, were long-necked plant-eaters. They are the heavyweights in the museum’s list because they were so long, with Argentinosaurus alone weighing ten times a T. rex on the museum’s numbers.
The big predators sit in the middle of the table at 12 to 14 metres. Giganotosaurus is listed at 13m and 13.8 tonnes, heavier than a typical Tyrannosaurus at 12m and 7 tonnes. The museum notes that the largest T. rex specimens, Sue and Scotty, weighed over 8,000kg and were almost 13m long, so the biggest individual T. rex was much closer to Giganotosaurus than the “typical” figure suggests.
For the height question, our T. rex vs human size comparison explains why hip height (3.6-3.9m) and reared-up head height (6.5m and over) give two different answers.
Why these numbers are estimates
Most dinosaurs are known from incomplete skeletons, so lengths and weights are reconstructions. The museum states outright that the 14-metre length for Spinosaurus is an estimate because no complete skeleton has been found. Other figures can change as new fossils are found or methods improve, and different sources can quote different numbers for the same animal.
This page uses a single source (the Natural History Museum Dino Directory) for lengths and weights, so the table is internally consistent. If you see a different number elsewhere, it may be a different specimen, a different method or a different date of publication.
Compare other big things
For a living giant, see blue whale size compared to everyday things. For a tall animal that you can see today, see how tall a giraffe is compared to a human. On the comparison board, you can add any of 36 dinosaurs to a line-up next to a person, a bus or a landmark.
Method and sources
Lengths and weights come from the Natural History Museum Dino Directory pages for each animal, read on 25 October 2026. The directory does not list a weight for Stegosaurus. T. rex hip height (3.6-3.9m) comes from Encyclopaedia Britannica, as used in this site’s T. rex article. UK average man height (178.21cm) is from this site’s dataset, compiled from NCD-RisC. The cricket pitch (20.12m) and tennis court (23.77m) lengths are from the sports’ standard rules. Ratios divide the length by 178.21cm, 20.12m or 23.77m and are rounded; feet are metres multiplied by 3.28 and rounded. Hip heights on the board for Compsognathus and Velociraptor are approximate. Last reviewed 25 October 2026.
Open the comparison board to line up dinosaurs against people, or use the height converter to switch between metres and feet.