A/N: I'm sorry this isn't actually another chapter, but it may come in useful for some of the stories that I will be posting here. There will be more chapters! I plan to write one for each family grouping in the Company but, given how slowly I write, it could take a few years.
So, for the moment, try to imagine that Balin is explaining to Bilbo about dwarf ages...
The matter of dwarf ages is rather confusing and everyone has their own ideas about how they match up with human ages.
Based on what I've read in Tolkien's writings and what fits with the films etc, it doesn't seem possible to make a simple comparison (e.g one human year = 3 dwarf years).
While dwarves certainly age much more slowly than humans, it appears that they go through several stages of growth as follows:
1. Relatively fast growth from birth to age 30 (when they are considered old enough to fight) and 40 (when they reach adult appearance).
2. Slow ageing from 40 until around 240 (at which point they reach old age).
3. Rapid ageing from 240 to 250 (the usual life span of a dwarf, although a few live to 300).
In the absence of any 'official' guidelines, I am using my own reckoning as noted below (dwarf age = rough human age). However, this is just an approximation as the two species are not really comparable.
10 = 5
20 = 10
30 = 15
40 = 18
50 = 20
100 = 30
150 = 40
200 = 50
240 = 60
250 = 70