The numerator (top number of the fraction) should be recited like a cardinal number. The denominator (bottom number of the fraction) should be recited like an ordinal number.

Unless the numerator is one, make sure to put the denominator in plural form.

1/3 = one third

2/3 = two thirds

1/100 = one one hundredth

12/16 = twelve sixteenths

There are just two important exceptions:

1/2 = one half (not one second)

1/4, 2/4, 3/4 = one quarter, two quarters, three quarters (although saying “one fourth,” “two fourths” or “three fourths” would also be acceptable)