permill

Permill is a unit of measurement representing one part per thousand. It is often used in statistics, finance, and science to express proportions or rates. The symbol for permill is ‰, which resembles a percent sign (%) with an extra zero.

To convert a value to permill, you multiply the fractional or decimal value by 1000. For example, 0.1 is equivalent to 100 permill (0.1 * 1000 = 100‰). Similarly, 50% is equal to 500 permill (0.50 * 1000 = 500‰).

Permill is commonly used in contexts where percentages might be too large or too small to express a rate conveniently. For instance, the salinity of seawater is often measured in permill, typically around 35‰, meaning 35 grams of salt per kilogram of seawater. In finance, interest rates or fees might be quoted in permill if they are very small. In environmental science, concentrations of pollutants or dissolved substances can be expressed using permill. While less common than percentages, permill provides a useful intermediate scale for expressing fractional relationships.