Writing Tip: Spelling Out Centuries

Ordinal numbers with centuries should always be spelled out:

  • the twenty-first century

However, since this can take up a lot of space, feel free to substitute numerals where appropriate (H1s, email subject lines, or other scenarios where space is at a premium):

  • the 21st century

If the century is used as an adjective (typically placed before the noun), use a hyphen. If it stands alone or comes after the noun, remove the hyphen.

  • I love literature from the twentieth century.
  • I love twentieth-century literature.

For parts of centuries, only hyphenate when it’s used with “mid-”. “Early” and “late” should be left without hyphens.

  • This book was written in the mid-twentieth century.
  • This book was written in the early twentieth century.
  • Mid-twentieth-century literature is valuable.
  • Early twentieth-century literature is valuable.

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