T. rex’s height depends on which posture you mean. In its normal, roughly horizontal walking stance, hip height was about 3.6-3.9 metres (12-13ft) — over twice an average UK man’s 1.78m. If it reared fully upright, which wasn’t its typical posture, its head could have reached more than 6.5 metres (21ft).
T. rex size vs human and a double-decker bus
The table sets both T. rex figures against an average UK adult man and against a double-decker bus, one of this site’s real built reference heights.
| Subject | Height | vs UK average man (1.78m) |
|---|---|---|
| T. rex, hip height (normal walking posture) | 3.6-3.9m (12-13ft) | about 2.1x taller |
| T. rex, head height if reared fully upright | 6.5m+ (21ft+) | about 3.7x taller |
| UK average man | 1.78m (5’10”) | — |
| Double-decker bus | 4.39m | 2.5x taller |
Hip height alone (3.6-3.9m) sits close to but a little under a double-decker bus’s 4.39m roof. The reared-up figure (6.5m+) clears the bus by well over two metres.
Why “how tall was T. rex” has two answers
T. rex didn’t stand upright as its default posture. Its normal walking stance held the body roughly horizontal, balanced over the hips by a long, heavy tail, with the head extended forward rather than held high.
In that normal posture, the relevant “height” figure is hip height off the ground: about 3.6-3.9m, per Britannica. That’s the figure that best represents how tall a T. rex would actually have looked standing next to you in life.
The much larger figure — 6.5m or more to the top of the head — only applies if the animal reared up into a fully vertical stance, tail down, head raised. That wasn’t its everyday posture, so treating 6.5m as “T. rex’s height” without qualification is misleading, even though it’s a genuine, sourced figure for the reared position.
| Name | Height |
|---|---|
| Average UK man | 178.2 cm |
| Double-decker bus | 439 cm |
| T. rex (hip, about 3.7m) | 370 cm |
How the silhouette on this page is scaled
The comparison board normally draws each silhouette so that its whole outline, from the lowest point to the highest, matches the height you give it. For a person that is simply their standing height. For a T. rex, which held its body roughly horizontal, the honest “height” depends on which point you measure. So for animals and dinosaurs the board can measure to the shoulder or hip instead: the outline is drawn taller so that point lands on the height you give, and a dashed line marks it. This page uses the 3.7m midpoint of the sourced hip-height range. Where the hip sits on each outline is estimated from the artwork, so it is approximate.
Use the comparison board to try other values yourself: 3.6m or 3.9m for the hip-height range, or 6.5m to see the reared-up posture the article discusses. The board’s library has 36 dinosaurs, including Triceratops, Spinosaurus and Velociraptor, and the article on biggest dinosaurs compared to a human compares their lengths.
How big T. rex actually was
Beyond height, T. rex is generally described in the palaeontological literature as one of the largest land predators known, with substantial body mass to match its length and height figures. Its skull alone was large and heavily built, suited to a powerful bite.
The hip-height figure of 3.6-3.9m already places T. rex’s back well above the head of even a tall adult human. Standing next to a fully grown T. rex in its normal posture, most adults would find the top of the animal’s hip roughly level with, or a little above, their own head.
Comparing dinosaur and human proportions fairly
Human height is conventionally measured standing fully upright, top of head to the floor. Applying that same convention to a horizontally postured animal like T. rex, using hip height, is the fairer like-for-like comparison — it reflects the animal’s actual normal stance rather than an exaggerated pose.
That’s why this article leads with hip height (3.6-3.9m) as the primary figure, and presents the reared-up head height (6.5m+) as a clearly labelled secondary figure rather than the headline number. Both are genuine, sourced measurements; they simply answer different questions.
This same posture issue is part of why dinosaur size comparisons online can vary so widely — a “T. rex height” quoted without specifying posture could reasonably mean either figure, which is why this page states both explicitly.
Method and sources
T. rex height figures — hip height of approximately 3.6-3.9m (12-13ft) in normal posture, and a reared-up head height exceeding 6.5m (21ft) — come from Encyclopaedia Britannica’s “How Tall Was T. rex?” article, cited above.
UK average adult male height (1.78m) comes from this site’s own country dataset, compiled from NCD-RisC’s 2019 cohort figures, used consistently elsewhere on this site. Double-decker bus height (4.39m) comes from this site’s own built asset library (src/data/assets.json), sourced there from a London New Routemaster bus specification. The T. rex silhouette is from the same library.
All ratios above (T. rex-to-human, T. rex-to-bus) are simple division from these sourced figures. Last reviewed 2026-10-25.
Open the comparison board to stand a UK average man and a double-decker bus side by side and add your own reference height, or try the height converter to switch any of these figures between metric and imperial.
See also: biggest dinosaurs compared to a human.