One half-inch or one-half inch

Answer 1

"one half-inch" - Grammatically, wrong. One-half anything is correct, but usually 1/2" or even 0.5 inches or 0.5" are far more meaningful to most readers. If we customarily used half-inch as a unit of measure, one half-inch would be sensible as would one half-pint if we used half-pint as a standard unit of measure. But, since we do neither as a general rule, one-half pint, one-half inch, and one-half gallon (except possibly in the case of milk!) would be "standard" (we are no longer allowed by the PC monitors to use "correct" and "incorrect"). Ah, what happened to our promised change to the metric system? Here's a handy test to determine best usage: If you say I have a piece of material that is one half-inch long, wouldn't it then follow that another piece three times as long would be described as being three half-inches long? I think not.

Answer 2

"One half-inch" is the correct way to express a measurement of half of an inch. It is written as a fraction to indicate the size or quantity.