Per mil
A per mil, per mille, or per mill (rarely spelled permil or permille) (Latin, literally meaning 'for (every) thousand') is a tenth of a percent or one part per thousand. It is written with the sign ‰ (Unicode U+2030, html entity ‰), which looks like a percent sign (%) with an extra zero at the end. It can be seen as a stylized form of the three zeros in the denominator although it originates from an alteration of the percent sign.
The term is so rarely used in English that major dictionaries do not agree on the spelling or pronunciation (even within one kind of English) and often do not list the other variants or do not even have an entry (for example Chambers, Longman, and Macmillan).[1][2][3][4][5] The term is very common in most other languages, for example in expressing blood alcohol content, which is always expressed in percent in English-speaking countries.
A per mil is defined as:
- 1‰ = 10−3= 1⁄1000 = 0.001 = 0.1%
- 1% = 10‰
A per mil should not be confused with ppm (commonly pronounced "parts per million" in the United States). A measurement in ppm means parts per million, and has as its denominator 1,000,000 and not 1,000.
[edit] Examples
Examples of common use include:
- Legal limits of blood-alcohol content for driving a road vehicle in some countries are 0.5‰ or 0.2‰.
- Seawater salinity. For example "the average salinity is 35‰".
- Tunnel and railway gradients (in some countries)
- Birth and death rates.
- Baseball batting averages, colloquially
- When used to describe property taxation, it is called the millage rate (U.S.) or mill rate (Canada).
- Used to describe stable-isotope ratios. For example "δ13C was measured at -3.5‰"
[edit] Related units
- Percentage point
- Percent (%) 1 part in 100
- Basis point (‱) 1 part in 10,000
- Parts-per notation
[edit] References
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