Using Commas with Numbers


 
Commas can be used with large numbers to assist the reader. They are placed every three decimal places to the left of the decimal point. For example:

  • 123,456.789
(Be aware that most other countries use a comma for the decimal point and full stops / periods to mark out every three decimal places.)
 

Using Commas with Numbers

Commas can be used to make reading numbers a little easier. They are placed every 3 decimal places for numbers larger than 999.

Examples:

  • 1,234

  • 23,566

  • 1,234,967

  • Serial number 1654880 was destroyed in 1984.
  • (Do not put your own commas in reference numbers or years.)
 
NO COMMAS TO THE RIGHT OF THE DECIMAL POINT

Do not use commas to the right of the decimal point.

  • 4,567.123456

  • 4,567.123,456
  • (This would be considered unusual.)
 
 
BEWARE OTHER CONVENTIONS

The use of commas and full stops in numbers is not consistent across the world. Below are the three most common conventions:

  • 4,567.1
  • (United Kingdom, United States, China)
  • 4.567,1
  • (This convention is used in most of Europe. It is the convention used by most countries.)
  • 4 567,1
  • (This convention is also common. It features in most of the countries which use the convention directly above.)
 

See also:

Numbers as compound adjectives
How to write numbers in full
Starting sentences with numbers
Commas after a sentence introductions
Commas after a transitional phrase
Commas after interjections (yes, no, indeed)
Commas before conjunctions (and, or, but)
Commas for parenthesis
Commas in lists
Commas with a long subject
Commas with quotation (speech) marks
Commas with the vocative case
Commas with Dear, Hello, and Hi
List of easily confused words