Cortisol: normal range and what it means
The primary stress hormone — follows a daily rhythm (morning value).
Normal range
Adult reference range.
- Low< 6 µg/dL
- Normal6 – 18.4 µg/dL
- High≥ 18.4 µg/dL
What it measures
Your main stress hormone, highest in the morning. Chronic elevation affects sleep, weight and immunity.
What moves it
Stress, sleep, time of day, caffeine and illness.
How to bring it into range
Sleep, stress management, limiting late caffeine. Test in the morning.
How fast it responds
Varies hour to hour; trends over weeks.
Also reported as: serum cortisol · morning cortisol
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Common questions
- What is a normal Cortisol level?
- Normal: 6 – 18.4 µg/dL. Adult reference range.
- What does a high Cortisol mean?
- A value above the reference band means Cortisol is outside the range typical for a healthy adult. A single reading is rarely conclusive on its own — what matters is the trend across draws and the other markers around it, which is why HealthOS reads the whole panel together rather than one number at a time.
- How do I improve my Cortisol?
- Sleep, stress management, limiting late caffeine. Test in the morning.
More in Hormones
Reference ranges are general-population guidance compiled from common clinical laboratories, not a diagnosis. Lab-to-lab ranges differ. Always read your results with your doctor.