ppth
part per thousand
Concentrationexact by definition
A part per thousand is 0.1%, also written per mille or ‰. Salinity is the classic use: seawater is about 35 ppth, which is the number oceanographers wrote as 35‰ for most of the twentieth century. Blood alcohol limits in much of Europe are set in per mille as well.
Watch out: Modern oceanography abandoned the symbol. Practical salinity has been a dimensionless ratio since 1978 and is written 35 PSU or just 35, deliberately without a unit, because it is defined by conductivity rather than by mass of dissolved solids.
| 1 ppth | 0.1 % |
Solvers that use concentration