Per mille

The phrase per mille (from Latin per mīlle 'in each thousand') indicates parts per thousand. The associated symbol is ‰, similar to a per cent sign % but with an extra zero in the divisor.

Major dictionaries do not agree on the spelling, giving other options of per mil, per mill, permil, permill, permille.

The word promille is the cognate in Dutch, German, Finnish and Swedish, and is sometimes seen as a loanword in English with the same meaning as per mille.

The symbol is included in the General Punctuation block of Unicode at U+2030 ‰ PER MILLE SIGN. There is also an Arabic-Indic per mille sign at U+0609 ؉ ARABIC-INDIC PER MILLE SIGN.

Promille and permille are likely best known as shorthand terms for Blood Alcohol Concentration, where 1 promille corresponds to 1 gram of alcohol per liter of blood. Promille is used in the legal limits of blood-alcohol content for driving a road vehicle in some countries: for example: 0.5‰ or 0.8‰.

Cost per mille (CPM), the price of 1000 units, may be used for views of banner and display advertising, and for emails delivered by email service providers.

In UK insurance usage, the cost per mille is the rate per £1000 of insured value. In India, the premium per mille is the rate expressed as thousandths of the sum assured.

Gradients (in some countries in Europe) may be expressed as mm/m or m/km, and written with the per mille symbol.