Per mille sign ‰

1‰ = 1/1000 = 0.1%. To convert, move the decimal point one place: 25‰ = 2.5%, and 0.8% = 8‰.

Where you’ll see it:

• Ocean salinity: seawater averages about 35‰, roughly 35 grams of salt per kilogram of water.
• Blood alcohol content: many European countries state legal limits in ‰, such as 0.5‰. The US writes the same quantity as a percentage, so the 0.08% limit used in most states would be 0.8‰.
• Demographics: birth and death rates are usually quoted per 1,000 people; ‰ is the symbol form.
• Railways: some countries mark track gradients in ‰.

The per-ten-thousand sign ‱ corresponds to a basis point in finance (0.01%), but US financial writing almost always says “bps” or “basis points” instead.

Many US readers rarely see ‰ and may read it as %, which makes a value look ten times larger. In content for a general US audience, convert to percent or write “per thousand” the first time.

• Excel: there is no built-in per mille format. Multiply the value by 1,000 in a helper column and add the sign with a custom number format such as 0.0"‰".
• Word: Insert > Symbol, or the Alt+X code in the table above.
• LaTeX: \textperthousand.
• Phones: copy it from this page and save a text replacement such as “prml” → ‰.
• Data: store the plain number (0.005 or 5) and note the unit in the column header, so calculations never have to parse a symbol.