ppb
parts per billion
Concentrationexact by definition
Parts per billion is one part in 1e9, or exactly 1e-7 percent, and the factor is exact by definition. In dilute aqueous work it is taken as one microgram per litre, on the same density argument that makes ppm equal mg/L. It is the reporting range for lead, arsenic, mercury, disinfection byproducts and most trace organics in drinking water.
Watch out: Billion is not universal. The short-scale billion of 1e9 is what ppb means in all modern scientific and regulatory usage, but older British and continental European sources used a long-scale billion of 1e12. Where any doubt exists, μg/L is unambiguous and ppb is not, which is why regulatory limits are increasingly written in μg/L.
| 1 ppb | 1.0000000e-07 % |
Solvers that use concentration