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 | 1.0000000e-07 |
One parts per billion in every concentration unit
| 1,000 | part per trillion (ppt) | |
| 1,000 | nanogram per liter (ng/L) | |
| 1 | parts per billion (ppb)this unit | |
| 1 | microgram per liter (μg/L) | |
| 0.001 | parts per million (ppm) | convert → |
| 0.001 | part per million by volume (ppmv) | |
| 0.001 | milligram per kilogram (mg/kg) | |
| 0.001 | milligram per liter (mg/L) | |
| 0.000058418 | grain per US gallon (as CaCO₃) (gpg) | convert → |
| 0.000001 | part per thousand (ppth) | |
| 0.000001 | gram per liter (g/L) | |
| 1.00000e-07 | percent (%) | convert → |
| 1.00000e-07 | percent by weight (% w/w) | |
| 1.00000e-07 | percent by volume (% v/v) | |
| 1.00000e-07 | percent weight per volume (% w/v) | |
| 1.00000e-09 | fraction (0–1) (fraction) |
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