Use figures and spell out words like inches, feet, yards, etc., to indicate depth, height, length, and width. You should hyphenate adjectival form before nouns. For example,
- He is 5 feet 6 inches tall.
- The 5-foot-6-inch man.
- The 5-foot man.
- The basketball team signed a 7-footer.
- The truck is 17 feet long, 6 feet wide, and 7 feet high.
- The room is 9 feet by 12 feet.
- The 9-by-12 room.
- The storm left 5 inches of rain.
- The building has 7,000 square feet of floor space.
Use an apostrophe to indicate “feet” and quotation marks to indicate “inches” (6’5’’) only in very technical senses.