Grammar and mechanics · mechanical · v4.6.1

GRM-06

Hyphenate number-unit compound modifiers before nouns. The unit takes singular form when hyphenated.

Pass example

Start your 30-day free trial. | We offer a 2-hour workshop. | It's a one-time offer.

Fail example

Start your 30 day free trial. | We offer a 2 hours workshop. | It's a one time offer.

Relevant content types

Version history

  1. v4.6.1 · 2026-04-23

    Per-standard version tracking introduced. Every standard starts at the library version current at introduction; bump per-standard when the rule text, examples, or content_type_notes change.

Related standards

Other standards in the Grammar and mechanics category.

  • GRM-01 — Use the serial comma (Oxford comma) in lists of three or more items.
  • GRM-02 — Spell out abbreviations and acronyms on first use in body copy and help content. Use the short form for subsequent mentions. Universally understood abbreviations (FAQ, URL, ZIP, LLC, IRS) and regulated accessibility terms (TTY) do not require expansion in any context. Internal or organization-specific abbreviations should always be expanded on a public-facing page. If the surrounding copy acknowledges the reader may not know a term, expand it.
  • GRM-03 — Use exclamation points sparingly. Never use more than one at a time, and never in error messages or alerts.
  • GRM-04 — Don't use ampersands in body copy unless they are part of a brand name. Ampersands are acceptable in headings, navigation labels, footer links, and other space-constrained UI elements where '&' is a conventional shorthand.
  • GRM-05 — Use numerals for numbers in body copy. Spell out a number only when it begins a sentence.

← The content model