mg/kg
milligram per kilogram
Concentrationexact by definition
The milligram per kilogram is exactly one part per million by mass, 10⁻⁴ percent, and unlike mg/L it needs no assumption about density. Soil contamination, food additives, feed composition and metal impurities in alloys are all reported in mg/kg.
Watch out: This is the unit to reach for when the medium is not water. A soil result in mg/kg is a true ppm; the same number in mg/L would depend on how the sample was extracted and diluted. For solids, mg/kg and ppm are interchangeable without qualification.
| 1 mg/kg | 0.0001 % |
Solvers that use concentration