I’m in the last stages of publishing a highly-technical manuscript for a client. As part of my standardization, I have to make sure that the way the author expresses units of measure is not only consistent but also verify that it should be expressed as a singular or plural unit of measure.
Before this project, I honestly didn’t give much thought to the difference between “2 feet” and “2-foot” or “10 inches” and “10-inch.”
Here’s a down & dirty way to remember:
The singular, with a dash between the number and the singular form of the measurement, is used when you’re talking about a unit of measure. For example, a 10-inch section of board or a two-foot gap.
The plural is used when you’re talking about how many. For example, space the nails 10 inches apart.
The same works with metric (centimeter, meters, etc.) as well! What I discovered is that anytime I was unsure of the author’s exact meaning, I would read the sentence aloud and try it out both ways.
I need a twelve _____ long board.
a. foot b. feet c. –foot d. –feet
Space the cups six ____ apart.
a. –inches b. inch c. inches d. -inch
Please hand me the six ____ stapler.
a. inch b. –inch c. inches d. -inches