I am not good with numbers or estimating difference in numbers, so none will be mentioned in this post. I know some heights are giving in the supplemtary Chronicles books, but I am not using them. I am going off screenshots from the films. None of these images belong to me! I own nothing!
Thorin and Kili are two of the tallest dwarves in the Company. Thorin is slightly taller than Kili:
Now we are going to look at Thorin in comparison to other characters.
Thorin and Elrond:
Before looking at Thorin with other tall characters, we are going to look at him with Bilbo, so we can get a sense of Bilbo's height:
The top of Bilbo's head comes up to about the middle of Thorin's nose.
This difference is visible when looking at Bilbo and Elrond:
The top of Bilbo's head is slightly above Elrond's elbow.
Thorin and Bard:
Thorin and Thranduil:
Remember, Thranduil is the same height as Bard:
Thranduil and Bard are slightly shorter than Elrond, because Thorin's head comes up to the bottom of their armpits.
To put Tauriel and Kili's height difference into context, we need to look at both her height and Legolas's in comparison to each other and Thranduil.
Legolas and Thranduil:
Tauriel and Legolas:
Tauriel is shorter than Legolas, with the bottom of his nose about level with the bottom of her forehead.
As you can see, the top of Tauriel's head is about level with the bottom of Thranduil's chin.
This is the correct scale. Looking at the first picture of Tauriel and Thranduil, if you draw a line in your mind from the bottom of her nose over, it intersects just below Thranduil's armpit; slightly lower than where Thorin's head does.
Hopefully this is a helpful guide to the different heights in Middle-earth.