How big is a T. rex next to a grizzly bear?
A T. rex measures 12 m (39.4 ft) end to end, and a grizzly bear measures 2.5 m (8.2 ft) from the ground up. A T. rex comes to 4.80 times the measured size of a grizzly bear, a difference of 9.5 m (31.2 ft). The two are not judged on the same axis: a T. rex is quoted as a length and a grizzly bear as a height, so the honest statement is one figure against the other, 21% of it, and not one outline against another. A T. rex is written in tens of metres and a grizzly bear in single metres, a whole band of scale apart.
| Object | Real size | Axis measured | What the figure covers |
|---|---|---|---|
| T. rex | 12 m 39.4 ft |
Length | Average Adult |
| Grizzly Bear | 2.5 m 8.2 ft |
Height | Average Male |
Both figures, T. rex and Grizzly Bear, come from the Size It Up measurement set, one real-world size and one measured axis per object, last checked in September 2026; outline provenance is listed on the sources page.
Why this one is hard to judge by eye
A T. rex is drawn about 11.1 times as wide as a grizzly bear as well as 4.80 times its measured size, so the area it takes in the frame grows faster than the figure anyone quotes. A T. rex sits in the range with no handy yardstick: too big to hold against anything you have carried, too small to need a horizon, so it and a grizzly bear end up filed under the same vague heading of very large. On the drawing above a T. rex is about 2.39 times as wide as it is tall and a grizzly bear about 2.32 times as tall as it is wide, so the two outlines fill the frame in ways that have nothing to do with the one axis being compared.
What each figure covers
T. rex. T. rex is quoted nose to tail. Specimens differ by metres, and the largest known individual is considerably longer than the average used here.
Grizzly Bear. This is the upright height, the bear standing on its hind legs. On all fours the same animal is roughly half that, which is why the two figures are so often confused.
A T. rex is quoted as a length and a grizzly bear as a height: two conventions, so the ratio compares the two numbers rather than the two objects.
What else is about that size?
Measured the same way, T. rex at 12 m sits within a tenth of Whale Shark at 12.1 m, X-wing Starfighter at 12.5 m and Modern London Double-Decker Bus at 10.9 m. Grizzly Bear at 2.5 m has London Phone Box at 2.51 m, Thanos at 2.52 m and Ostrich at 2.4 m for company, within a tenth. Swapping any of those in for a T. rex would move its ratio to a grizzly bear by less than 10%.