InuYasha: 15 (in human years) 222 (chronologically)
A half-demon born from a demon father and a human mother. After winning the battle against Naraku over the Shikon Jewel, Kagome has returned to the Warring States period.

Kagome: 15 (InuYasha) 18(TFA) 24(Birth) 38(Yashahime)

Miroku: 18 (InuYasha) 21(TFA) 41(Yashahime)

Sango: 16 (InuYasha) 20(TFA) 39(Yashahime)
Kohaku: 11 (InuYasha) 14(TFA) 34(Yashahime)
Sesshoumaru: 19 (in human years) Hundreds of years old (chronologically)
Rin: (No Official Age) Estimated 8-9 (InuYasha) 12-13(TFA) 17-18(Birth) 31-32(Yashahime)
Towa: 14 (Oldest)
Setsuna: 14 (Middle)
Moroha: 14 (Youngest)

More to be added soon

These ages are as accurate as possible and are taken straight from the source material including the Official InuYasha Profiles book, which are then calculated from the timeskips. The descriptions are translated from the Official Yashahime website.