Nanograms per Litre to Milligrams per Litre
1 ng/L is 0.000001 mg/L, and 1 mg/L is 1,000,000 ng/L. This conversion spans the gap between what a modern trace method can detect and the scale most drinking-water limits are written at.
Adjust the inputs and select Calculate for a full breakdown.
Solution method, checks and interpretation
Nanograms per Litre to Milligrams 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 |
|---|---|---|---|---|---|
| A PFAS result: 20 ng/L — 0.00002 mg/L | 0.00002 | 0.000001 | 0.00000002 | 0.00002 | 0.02 |
| A nitrate limit: 10 mg/L — 10,000,000 ng/L | 10,000,000 | 1,000,000 | 0.01 | 10 | 10,000 |
| A residue: 150 ng/L — 0.00015 mg/L | 0.00015 | 0.000001 | 0.00000015 | 0.00015 | 0.15 |
How This Calculator Works
A milligram holds a million nanograms and the litre is unchanged, so the million carries through. Multiply ng/L by 10⁻⁶ to get mg/L.
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 PFAS result of 20 ng/L is 0.00002 mg/L. A nitrate limit of 10 mg/L is 10,000,000 ng/L. A pharmaceutical residue at 150 ng/L is 0.00015 mg/L — a number no regulation would ever be drafted in.
Key Insight
The million-fold gap is itself the finding. When a contaminant is measured in ng/L and regulated in mg/L, the result is six orders of magnitude below the limit before anyone does any arithmetic, and the interesting question stops being compliance and becomes whether the limit was set at a scale the health evidence supports. Several classes of contaminant have moved the other way in recent years — advisories drafted in ng/L precisely because mg/L could not express them. A conversion that produces five leading zeros is telling you the two numbers came from different eras of analytical chemistry.
Frequently Asked Questions
How many mg/L is 1 ng/L?
0.000001 mg/L. A milligram is a million nanograms and the volume is the same on both sides.
How do I convert mg/L to ng/L?
Multiply by a million. A 0.01 mg/L limit is 10,000 ng/L.
Why would a result be reported in ng/L at all?
Because the method can detect that far down and the number would otherwise be all zeros. A 20 ng/L result written in mg/L is 0.00002, which is an invitation to lose a decimal place.
Is ng/L the same as parts per trillion?
In dilute water they are used interchangeably, but parts per trillion is a mass per mass and the equivalence runs through the density of water.
What is 10 mg/L in ng/L?
10,000,000 ng/L. A typical nitrate limit expressed at trace scale, which shows why nobody does it.
Does this conversion depend on the contaminant?
No. It is a ratio of SI prefixes and holds for every substance.
Related Calculators
Embed this calculator
Add this calculator to your website for your readers. The embed includes a neutral attribution link to the original CalcDomain page for methodology, updates, and source notes.
Attribution uses rel="nofollow" by default and is included for transparency, not ranking manipulation.
Suggest an improvement
Found a calculation issue, outdated source, unclear assumption, or missing edge case? Send a short note so we can review it.
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.
- Parts per trillion is not offered: it is a mass per mass and reaching it divides by a density.
- A result below a method detection limit stays below it after conversion. The unit change makes the number larger, not the measurement better.
- 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
Both sides are per litre, so the factor is the ratio of the two mass prefixes: a milligram is a million nanograms. Derived from the SI prefix exponents, exact, and independent of the analyte. 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.
Updated