And I thought Gimli was born 10 years AFTER The Hobbit? Is he really going to be in the movie?
Gimli was 62, considered still a callow youth in Dwarf terms "although I thought myself ready for anything.". Kili, the youngest of the party, was 77. Thorin was 195 and Gloin 158; interestingly, "old" Balin was years younger than Thorin.
Using a 3.5 multiplier as a very rough guide to human age equivalents, Thorin was 56, Balin 51, Gloin 45, Kili 22 and Gimli a kid of 17.