Åk 6–9
5.2 Per Mille
Per mille is a term for a thousandth. The sign (‰) is often used to designate per mille.

1/1,000 = 1 ‰

When you want to compare parts which are very small, in relation to the whole, you often use thousandths (per mille) instead of hundredth (per cent).

Percent (%) means: how much of  ”a hundred”, or how many ”per hundred”.
Per mille (‰) means: how much of ”a thousand”, or how many ”per thousand”.

Per mille (thousandths) is used for example to describe how many children are born or how many people who die, for every thousand inhabitants in a country.  It is also used to measure how large a proportion of alcohol there is in the blood of a person who has drunk alcohol.  Per mille is also used to describe how much salt there is in salt water.

In the Baltic Sea, 1,000 grams of saltwater contains 7 grams of salt. This means that the proportion of salt in comparison to water is 7 thousands, 7 grams of 1,000 gram = 7 per mille.