About

In biochemistry and pharmacology, understanding the molar concentration of a substance is often more clinically relevant than its mass concentration. This tool converts ng/mL (nanograms per milliliter) to nmol/L (nanomoles per liter). This conversion is strictly dependent on the Molecular Weight (MW) of the analyte.

For example, 25-Hydroxy Vitamin D is often reported in ng/mL in the US, but nmol/L in Europe and Australia. Comparing these results without conversion can lead to diagnosis errors regarding deficiency or toxicity. This utility includes a comprehensive database of steroid hormones, thyroid markers, and vitamins, ensuring the exact atomic mass is used for the calculation.

Formulas

The formula derives from the relationship between mass, volume, and molar mass. Since 1 ng/mL is equivalent to 1 μg/L, the equation simplifies to:

C_nmol/L = C_ng/mL × 1000MW

Where MW is the Molecular Weight in Daltons (g/mol). For example, converting Testosterone (MW ≈ 288.42):

1 × 1000288.42 = 3.467 nmol/L

Reference Data

Biomarker	Molecular Weight (g/mol)	Conversion Factor (×)
Testosterone	288.42	3.467
Progesterone	314.46	3.180
Cortisol	362.46	2.759
Estradiol (E2)	272.38	3.671
25-OH Vitamin D3	400.64	2.496
Thyroxine (T4)	776.87	1.287
Triiodothyronine (T3)	650.97	1.536
Aldosterone	360.44	2.774

Frequently Asked Questions

ng/mL measures the weight of the substance in the liquid (mass concentration). nmol/L measures the number of molecules in the liquid (molar concentration). nmol/L is scientifically more consistent for comparing biological reactions.

Yes. This is one of the most common uses. Select "25-Hydroxy Vitamin D" from the list. Note that 1 ng/mL equals approximately 2.5 nmol/L for Vitamin D.

Yes. If your specific drug or metabolite is not listed, select "Custom MW" and input the molecular weight (g/mol) manually.

Because every molecule has a different weight. A heavy molecule like T4 (MW ~777) contributes fewer moles per nanogram than a light molecule like Estradiol (MW ~272).