Enter a lab value in nmol/L (or mg/dL for the reverse direction) and choose the substance so the calculator can apply the correct molecular weight and convert between molar and mass concentration units.
Related Calculators
- All Unit Converters
- Mmol/L to mg/dl Calculator
- umol/l to mg/dl Calculator
- mg/dl to umol/l Calculator
Formula
mg/dL = (nmol/L × MW) ÷ 10,000,000
where MW = molecular weight in g/mol
nmol/L = (mg/dL × 10,000,000) ÷ MW
The factor 10,000,000 comes from unit reconciliation: 1 g = 109 ng, 1 L = 10 dL, and nmol → g requires dividing by 109 after multiplying by MW.
Interpretation
The output is the same concentration expressed in a different unit system. nmol/L is a molar unit (counts molecules per volume) and is standard in most of the world and in endocrine labs. mg/dL is a mass unit common in US clinical reports. Because the conversion depends on the molecular weight of the specific substance, the same nmol/L value produces very different mg/dL values for different analytes — a vitamin D reading and a cholesterol reading with identical nmol/L numbers will not have the same mg/dL result.
Typical reference ranges to sanity-check your result:
- Vitamin D (25-OH): 75 nmol/L ≈ 30 ng/mL (0.003 mg/dL) — sufficiency threshold.
- Total cholesterol: 5.17 mmol/L ≈ 200 mg/dL — borderline high.
- Glucose (fasting): 5.55 mmol/L ≈ 100 mg/dL — upper end of normal.
- Testosterone (male): 10–35 nmol/L ≈ 288–1009 ng/dL.
Common Molecular Weights
| Substance | MW (g/mol) | Example conversion |
|---|---|---|
| Vitamin D (25-OH) | 400.64 | 75 nmol/L = 30.05 ng/mL |
| Cholesterol | 386.65 | 5.17 mmol/L = 200 mg/dL |
| Glucose | 180.16 | 5.55 mmol/L = 100 mg/dL |
| Testosterone | 288.42 | 20 nmol/L = 576.8 ng/dL |
| Cortisol | 362.46 | 500 nmol/L = 18.1 µg/dL |
| Estradiol | 272.38 | 100 pmol/L = 27.2 pg/mL |
| Uric acid | 168.11 | 360 µmol/L = 6.05 mg/dL |
| Creatinine | 113.12 | 88.4 µmol/L = 1.0 mg/dL |
FAQ
Why does the answer change when I pick a different substance?
Molar units (nmol/L) and mass units (mg/dL) are linked by molecular weight. A heavier molecule weighs more per mole, so the same nmol/L produces a larger mg/dL value. You must match the substance to the analyte your lab reported.
My vitamin D result is reported in ng/mL, not mg/dL. How do I convert?
1 ng/mL equals 0.0001 mg/dL, or equivalently, 100 ng/mL = 0.01 mg/dL. For 25-OH vitamin D specifically, nmol/L ÷ 2.496 ≈ ng/mL. Most US vitamin D reports use ng/mL rather than mg/dL.
What if I don’t know the molecular weight?
Select the substance from the dropdown — the calculator loads the accepted MW automatically. Only use the custom MW field if you are converting a compound not listed (check a reference source like PubChem for the exact g/mol value).
Can I use this for mmol/L or µmol/L instead of nmol/L?
Not directly in this field, but the result panel shows µmol/L and mmol/L equivalents after calculation. To go the other way, multiply mmol/L by 1,000,000 or µmol/L by 1,000 to get nmol/L before entering.
