15 µg/dL cortisol to nmol/L

About cortisol and these units

Cortisol is a steroid hormone reported on endocrine and adrenal-function panels. Cortisol appears in µg/dL on US lab reports and in nmol/L on UK, Canadian, Australian, and most European lab reports.

Where the 27.59 conversion factor comes from

µg/dL is a mass-per-volume unit. nmol/L is a moles-per-volume (molar concentration) unit. To convert between them you need the molecular weight of the substance, because that determines how many moles of it fit into a given mass.

For cortisol, the reference molecular weight is 362.46 g/mol. Working through the unit algebra:

• The factor is fixed by the molecular weight (362.46 g/mol) together with the mass and volume prefixes of the two units, since a molar concentration counts molecules and a mass concentration weighs them.
• For cortisol this works out to 27.59 nmol/L per µg/dL (multiply µg/dL by 27.59 to get nmol/L).
• The inverse (nmol/L → µg/dL) is 0.0362.

Step-by-step: converting 15 µg/dL of cortisol by hand

1. Start with the lab value: 15 µg/dL.
2. Look up the conversion factor for cortisol: 27.59 nmol/L per µg/dL.
3. Multiply: 15 × 27.59 = 413.85.
4. Attach the SI unit: 413.85 nmol/L.

Inverse check: 413.85 nmol/L ÷ 27.59 = 15 µg/dL ✓.

Companion conversions for nearby cortisol values

If your lab reported a number close to but not exactly 15 µg/dL, the table below covers the surrounding range so you don't need to re-run the arithmetic.

A note on precision

Clinical chemistry assays for cortisol are typically precise to two or three significant figures. The exact factor 27.59 is itself a rounded number, and the molecular weight that produces it (362.46 g/mol) is conventionally rounded. So while the calculator displays 413.85 nmol/L for 15 µg/dL, reporting more decimal places than your original measurement supports is false precision.

Common questions

What is 15 µg/dL cortisol in nmol/L?

15 µg/dL of cortisol equals 413.85 nmol/L. The conversion factor for cortisol is 27.59 (multiply µg/dL by 27.59 to get nmol/L).

How do I convert µg/dL to nmol/L for cortisol?

cortisol has a conversion factor of 27.59. Formula: 15 µg/dL × 27.59 = 413.85 nmol/L. Inverse: 413.85 nmol/L ÷ 27.59 = 15 µg/dL.

Why does cortisol have a different conversion factor than other biomarkers?

Each biomarker's µg/dL ↔ nmol/L factor is set by its molecular weight, because nmol/L is a molar concentration. For cortisol, the reference molecular weight is 362.46 g/mol, which gives a factor of 27.59.

Where is µg/dL used and where is nmol/L used?

Cortisol appears in µg/dL on US lab reports and in nmol/L on UK, Canadian, Australian, and most European lab reports.

How precise should I report the converted value?

Lab assays for cortisol are typically precise to about two or three significant figures. Reporting more decimal places than your original measurement supports is false precision. For a reading of 15 µg/dL, 413.85 nmol/L is appropriate; further decimals are not.

Related conversions and reference

• Full blood test unit converter: convert any value for 50+ biomarkers in either direction.
• HbA1c ↔ average glucose converter: separate page for the HbA1c (% / mmol/mol) ↔ eAG conversion.
• Cholesterol ratio calculator: total/HDL and LDL/HDL ratios.