The phrase per mille 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. There is also an Arabic-Indic per mille sign at.

Examples

Blood alcohol concentration

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

Sales and marketing

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.

Insurance

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

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

Isotope ratios

Per mille may be used to express stable-isotope ratios—for example: "δ13C was measured at −3.5‰"

Taxation

Charity fraction

In Italy, it is possible to nominate a charity or charities to receive "five per mille" (5‰) of personal taxation payments.

Property tax

Property taxation rates may be expressed as the millage rate (U.S.) or mill rate (Canada), from mill (currency), one thousandth of a dollar.

Quantile

Permille may also be used to express a 1000-quantile ("999th permille"), but this usage is rare and largely obsolete. Modern publications instead use fractional percentiles ("99.9th percentile").

Salinity

Seawater salinity is often expressed per mille. Average marine salinity is about 35 parts per thousand or 35‰ (3.5%).

Related units