1/2 is read half / one half / a half
1/3 is read one third / a third
1/4 is read one fourth / a fourth / one quarter / a quarter
For the 1/5, 1/6, etc., we read "one" or "a" followed by the ordinal number: a fifth, a sixth, etc. Lots of luck pronouncing the final Th sounds after another consonant or consonant cluster :D