Fractions should always be hyphenated when they are adjectives or adverbs, as in They got a one-third share and The money is three-quarters gone. ... One can think of the hyphen as representing the division bar in a fraction in figures.

Should one half be hyphenated?

Do not hyphenate a half; hyphenate one-half. Hyphenate compound adjectives before a noun: a half-serious remark. Do not hyphenate such compounds when they follow a noun unless hyphenated in Webster's: He was only half serious. Do not hyphenate adverbs: half jokingly.

Do you hyphenate two thirds?

Use hyphens in fractions whenever they are written as words, whether they function as a noun (two-thirds is more than one-half), adjective (a two-thirds majority) or adverb (two-thirds finished).