Per mille different from parts per thousand
Per mille (from Latin  per mīlle 'in each thousand') is parts per thousand. Other recognised spellings include per mil, per mill, permil, permill, or permille.The associated sign is written ‰, which looks like a percent sign % with an extra zero or o in the divisor.
The term occurs so rarely in English that major dictionaries do not agree on the spelling and some major dictionaries, such as Macmillan, do not even contain an entry. The term is more common in other European languages where it is used to express fractions smaller than 1%. One common usage is blood alcohol content, which is usually expressed as a percentage in English-speaking countries.
Per mille should not be confused with parts per million (ppm).Related units
Percentage point difference of 1 part in 100
Percentage (%) 1 part in 100
Basis point (bp) difference of 1 part in 10,000
Permyriad (‱) 1 part in 10,000
Per cent mille (pcm) 1 part in 100,000See also
Parts-per notation
Per-unit system
Percent point function
Fineness of precious metals (given as "0.000-fine")