‰ Per Mille Sign: Meaning, History, and Usage Guide
The per mille sign (‰) is a mathematical symbol representing "per thousand," meaning one part in a thousand. Just as a percent sign (%) signifies a fraction out of 100, the per mille sign indicates a fraction out of 1,000, making it equivalent to 0.1%. It is frequently used in scientific, demographic, and financial contexts to express very small ratios accurately without using decimal points.
Historically, the symbol evolved directly from the percent sign. The term "mille" comes from the Latin word for thousand. By adding an extra zero to the traditional percent symbol, typographers created a visually intuitive way to denote a factor of ten smaller. In the Unicode Standard, the per mille sign is assigned the code point U+2030 and resides in the General Punctuation block.
While you might not see it in everyday text messages or casual social media posts, the ‰ symbol is a heavy hitter in specialized fields. Oceanographers use it to measure seawater salinity, while demographers rely on it to report national birth and death rates. In many European countries, blood alcohol content (BAC) is legally measured and reported in per mille rather than percent. You might also spot it in civil engineering to express the steepness or gradients of roads, tunnels, and railway tracks.
Typing the per mille sign doesn't require a specialized keyboard. On a Windows PC, hold down the Alt key and type 0137 on the numeric keypad. Mac users can easily insert it by pressing Option + Shift + R. On iOS and Android smartphones, you can usually find it by long-pressing the standard percent sign (%) on the on-screen keyboard. For web developers and writers working in HTML, the symbol can be generated using the named entity ‰ or the decimal code ‰.
The per mille sign belongs to a small family of proportional punctuation marks. Its most famous sibling is the standard percent sign (%), which measures parts per hundred. For even smaller fractions, there is the per ten thousand sign (‱), also known as a basis point, which adds yet another zero to the bottom of the design. Recognizing the visual and mathematical differences between these three ensures your data is perfectly accurate, whether you are tracking a financial return or analyzing an environmental study.