Nanograms per Millilitre to Micrograms per Litre
They are the same concentration. A result of 30 ng/mL is 30 µg/L. The factor is exactly 1, and laboratories in different countries report the same measurement in whichever of the two their convention prefers.
Adjust the inputs and select Calculate for a full breakdown.
Solution method, checks and interpretation
Nanograms per Millilitre to Micrograms per Litre is worked through as a complete solution: scenario, method, formula, substitution and interpretation.
Compare Common Scenarios
How the numbers shift across typical situations for this calculator:
| Scenario | Converted concentration | Factor applied | Same value in g/L | Same value in mg/L | Same value in µg/L |
|---|---|---|---|---|---|
| Vitamin D: 30 ng/mL — 30 µg/L | 30 | 1 | 0.00003 | 0.03 | 30 |
| A drug level: 12 µg/L — 12 ng/mL | 12 | 1 | 0.000012 | 0.012 | 12 |
| Testosterone: 4.5 ng/mL — 4.5 µg/L | 4.5 | 1 | 0.0000045 | 0.0045 | 4.5 |
How This Calculator Works
A nanogram per millilitre is 10⁻⁹ grams over 10⁻³ litres, or 10⁻⁶ grams per litre. A microgram per litre is 10⁻⁶ grams per litre. The thousand in the mass and the thousand in the volume cancel.
The Formula
Concentration conversion by prefix ratio
m and v are the base-10 exponents of the mass and volume SI prefixes of each unit. No density and no substance enter the calculation: the substance cancels between the two numerators, so 1 µg/mL is 1 mg/L for every solute in every solvent.
Worked Example
A 25-hydroxyvitamin D result of 30 ng/mL is 30 µg/L. A testosterone level of 4.5 ng/mL is 4.5 µg/L. A therapeutic drug level reported as 12 µg/L is 12 ng/mL — the same figure a US laboratory would have printed.
Key Insight
The risk here is not the arithmetic, it is the reference interval. Because the numbers are identical, a result in ng/mL can be read straight against a range quoted in µg/L and vice versa — but only if both came from assays that agree, and immunoassays for the same analyte often do not. Vitamin D is the standard example: the unit question is trivial and the assay question is not. Converting the number is free; assuming the interval travels with it is the error this page cannot prevent.
Frequently Asked Questions
Is ng/mL the same as µg/L?
Yes, exactly. Both are 10⁻⁶ grams per litre, so the factor is 1.
What is 30 ng/mL of vitamin D in µg/L?
30 µg/L. The number does not change. Note that nmol/L, which many laboratories also use, is a different matter entirely — it needs the molar mass.
Why do laboratories use different units for the same test?
Convention. US laboratories tend toward ng/mL and much of Europe toward µg/L or molar units; the first two are the same number and the third is not.
Can I compare my result to a reference range in the other unit?
The unit is not the obstacle — the number is identical. Whether the range applies depends on the assay that produced it, which is a different question and a more important one.
How do I get to nmol/L?
You cannot without the molar mass of the specific compound. 30 ng/mL of vitamin D and 30 ng/mL of testosterone are different nanomolar figures.
Is pg/mL to ng/L the same trick?
Yes. Every pair that scales mass and volume by the same thousand is an identity: µg/mL and mg/L, ng/mL and µg/L, pg/mL and ng/L.
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Assumptions
- The concentration is a mass of solute per volume of solution, which is the ordinary reading of these units in laboratory and regulatory reporting.
- The volume basis is the same on both sides. It always is in a unit conversion, and it is worth stating because it stops being true the moment a sample is diluted or concentrated.
Limitations & Disclaimer
This is an educational tool, not financial advice. It does not account for your personal circumstances, and no result is a guarantee.
- Molar units are not offered. nmol/L needs the molar mass of the specific compound and differs between analytes reported in the same mass units.
- A reference interval belongs to the assay that produced it and does not travel with a converted number.
- This does not convert to parts per million or parts per billion. Those are mass-per-mass quantities and reaching them from a mass per volume divides by a density, which is a property of the solution rather than a constant.
Methodology & Review
A nanogram per millilitre and a microgram per litre both work out to 10⁻⁶ grams per litre, so the factor is exactly 1. It is computed as a single power of a single integer exponent so that the identity returns 1 rather than a rounding artefact. No substance and no density enter the calculation: the solute appears in the numerator of both units and cancels.
External financial review: No independent third-party review. The relation follows from the definitions of the SI prefixes rather than from any measurement, and every golden vector below is exact..
Reviewed according to the CalcDomain Editorial Policy & Calculator Methodology. We document formulas, edge cases, sources, update dates, and correction paths for calculator pages.
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