Concentration converter
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Formula used
Direct mass conversion:
ppm = mg/kg
For mass-based concentration, one milligram per kilogram equals one part per million. The numerical value therefore stays unchanged when converting directly between mg/kg and ppm. This equivalence also applies to µg/g and g/tonne.
Wet basis to dry basis:
Cd = Cw ÷ (1 − M)
Dry basis to wet basis:
Cw = Cd × (1 − M)
How to use this calculator
- Enter the concentration value.
- Select the source and target units.
- Choose a moisture-basis adjustment when required.
- Set the preferred decimal precision.
- Add optional batch values for multiple conversions.
- Select Calculate conversion to display detailed results.
- Use Copy, CSV, or PDF/Print to save results.
Worked examples
| Input | Calculation | Result |
|---|---|---|
| 25 mg/kg | 25 × 1 | 25 ppm |
| 2.5 mg/g | 2.5 × 1,000 | 2,500 ppm |
| 0.02% | 0.02 × 10,000 | 200 ppm |
| 75 ppm wet basis, 20% moisture | 75 ÷ (1 − 0.20) | 93.75 ppm dry basis |
| 40 ppm dry basis, 15% moisture | 40 × (1 − 0.15) | 34 ppm wet basis |
Conversion reference table
| mg/kg | ppm | µg/g | g/tonne | mg/g | % | ppb |
|---|---|---|---|---|---|---|
| 0.001 | 0.001 | 0.001 | 0.001 | 0.000001 | 1.0000000000e-7 | 1 |
| 0.01 | 0.01 | 0.01 | 0.01 | 0.00001 | 0.000001 | 10 |
| 0.1 | 0.1 | 0.1 | 0.1 | 0.0001 | 0.00001 | 100 |
| 1 | 1 | 1 | 1 | 0.001 | 0.0001 | 1,000 |
| 10 | 10 | 10 | 10 | 0.01 | 0.001 | 10,000 |
| 100 | 100 | 100 | 100 | 0.1 | 0.01 | 100,000 |
| 1,000 | 1,000 | 1,000 | 1,000 | 1 | 0.1 | 1,000,000 |
Understanding mg/kg and ppm
Milligrams per kilogram expresses a substance mass inside a larger sample mass. Parts per million describes the same ratio when both quantities use compatible mass units. Therefore, 1 mg/kg equals 1 ppm by mass.
This relationship is widely used in soil testing, food analysis, animal feed, fertilizer evaluation, environmental monitoring, and laboratory reports. It allows values to move between technical and regulatory formats without changing their magnitude. Moisture correction is still necessary when sample bases differ.
Direct equality does not automatically apply to milligrams per liter or gas-volume concentrations. Those conversions may require density, molecular weight, temperature, or pressure. Always confirm whether the reported ppm is mass-based or volume-based.
Frequently asked questions
Is 1 mg/kg always equal to 1 ppm?
It is equal when ppm is expressed on a mass-per-mass basis. Other ppm definitions may require additional information.
Why does the direct result stay unchanged?
One kilogram contains one million milligrams. A concentration of one milligram in one kilogram is therefore one part per million.
Can this calculator convert ppm back to mg/kg?
Yes. Select ppm as the source unit and mg/kg as the target unit.
What does wet basis mean?
Wet basis includes the sample's water mass when expressing concentration. Dry basis removes that water contribution.
How is moisture entered?
Enter moisture as a percentage between zero and less than one hundred. The calculator converts it into a decimal fraction.
Are µg/g and ppm equivalent?
Yes, for mass-based concentration. One microgram per gram equals one milligram per kilogram and one ppm.
How do I convert percent to ppm?
Multiply the percent value by 10,000. For example, 0.01% equals 100 ppm.
How do I convert ppb to ppm?
Divide ppb by 1,000. For example, 5,000 ppb equals 5 ppm.
Can I convert several values together?
Yes. Enter multiple values in the batch box using commas, spaces, semicolons, or new lines.
Does the calculator accept scientific notation?
Yes. Numeric values such as 1e-6 are accepted by modern browsers and PHP numeric validation.
Can mg/L be converted directly to ppm?
Only under suitable density assumptions, commonly for dilute water solutions. This calculator intentionally focuses on mass-based concentration.