Colons in References, Times, Ratios, and Titles

Colons in References, Ratios, Times, and Titles

Colons are used as separators in references, times, ratios, and titles

Colons in References

In a biblical reference, a colon separates chapter from verse. For example:
  • Genesis 1:1 starts "In the beginning God created the heavens and the earth."
  • (Note there is no space before or after the colon.)
A colon is also used as a separator in a reading references. In a reading reference, the colon usually separates the volume from the page numbers.
  • This topic is covered in Encyclopaedia Britannica 3:21-23.
  • (This means volume 3 pages 21-23.)
Here is another example of colons used in a reference:
  • Learn Chapter XIV:Section 4:Paragraph 6 by tomorrow.
  • (There is no established format or ruling. Remember that colons in references are just separators for you to use.)

Colons in Ratios

A ratio between two or more quantities is a way of measuring their sizes compared to each other. A ratio is shown with a colon as a separator. For example:
  • It's myth that the ratio of women to men in Nottingham is 6:1.
  • 5:3 is close to the Golden Ratio, which is represented by the Greek letter phi (Φ)
The first number of a ratio is called the "antecedent." The second number is called the "consequent."


In times, colons are used in timings greater than a minute. For example:
  • The happiest hour of the day is between 19:00 and 20:00.
  • (Here, the colon separates hours and minutes.)
  • The marathon world record is 2:02:57.
  • (Here, the colons separate hours, minutes, and seconds.)
  • The 800m world record is 1:40.91.
  • (In this example, the colon separates minutes and seconds. Note that tenths of a second are not separated by a colon but a point.)
In times of the day, using a period or nothing is also a common convention. For example:
  • The alarm clock is set for 07:30.
  • (0730 and 07.30 are also common.)

Colons in Titles

In titles, a colon is often used to separate the main title from the subtitle. For example:
  • "Pirates of the Caribbean: Dead Man's Chest"
  • "How To Get Your Own Way: Who's Manipulating You?"
  • "Grammar Rules: Writing with Military Precision"
Note that a semicolon, a comma, and "or" are also commonly used to separate a title from a subtitle. Colons often make better separators than the alternatives.
colons as separators in references, times, ratios, and titles
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This page was written by Craig Shrives.