PPM to mg/kg Converter
Common Conversions
| ppm | mg/kg |
|---|---|
| 0.1 | 0.1 |
| 1 | 1 |
| 5 | 5 |
| 10 | 10 |
| 50 | 50 |
| 100 | 100 |
| 250 | 250 |
| 500 | 500 |
| 1000 | 1000 |
| 5000 | 5000 |
| 10000 | 10000 |
Why this conversion matters in chemistry
Soil and biosolid agriculture work crosses this identity. A soil-test phosphorus level of 35 ppm on the agricultural-extension report writes equivalently as 35 mg/kg on the EPA Method 6020B biosolids analytical data. The conversion is the standard type cast at the boundary between extension-style soil testing and EPA-method biosolids analytical reporting. The same equality holds for any solid-matrix mass ratio concentration: 1 ppm by mass = 1 mg per kg of sample, by direct definition.
Formula
mg/kg = ppm × 1 (numerically identical)
Worked Examples
1 ppm = 1 mg/kg
The conversion anchor — direct equivalence for ppm on a mass per mass basis.
100 ppm = 100 mg/kg
About a typical trace-metal soil-content level.
10 ppm = 10 mg/kg
About a typical heavy-metal limit in food-safety regulation.
1000 ppm = 1000 mg/kg
0.1% impurity level — the bridge between trace and bulk regimes.
Frequently Asked Questions
Is 1 ppm the same as 1 mg/kg?
Yes — exactly, when ppm is defined on a mass per mass basis. 1 part per million by mass = 1 mg per kg, by direct definition.
When is mg/kg preferred over ppm?
Analytical chemistry, soil science, and food-safety reporting prefer mg/kg because it explicitly states the mass per mass basis. ppm is more compact but ambiguous between mass per mass and mass per volume contexts.
Is mg/kg the same as µg/g?
Yes. 1 mg/kg = 1 µg/g — same ratio, different prefix combinations. The kilo and milli prefixes cancel in the same way the gram and micro prefixes do.
What are typical soil contaminant levels?
Background lead: 10–50 mg/kg. EPA residential soil-screening level for lead: 400 mg/kg. Agricultural cadmium limits: 1–3 mg/kg. The mg/kg scale spans the typical environmental and agricultural concentration range cleanly.