Cortisol Level Calculator
Enter your cortisol result and test time to compare against normal reference ranges — and understand how training, sleep, and stress affect your cortisol rhythm.
Cortisol Level Calculator
Compare vs normal reference ranges by time of day
Cortisol follows a diurnal rhythm: peaks within 30–45 min of waking (cortisol awakening response), then declines throughout the day. Always take blood cortisol in context of the time drawn.
Normal Cortisol Ranges by Time of Day
| Time | Normal (mcg/dL) | Normal (nmol/L) |
|---|---|---|
| Morning (6–10 AM) | 6–23 | 140–690 |
| Afternoon (12–6 PM) | 2–11 | 50–300 |
| Evening (6–10 PM) | 1–8 | 30–220 |
| Night (10 PM–6 AM) | <5 | <140 |
How Cortisol Affects Athletic Performance and Recovery
Cortisol is a glucocorticoid hormone produced by the adrenal cortex in response to physical and psychological stress. It plays essential physiological roles — mobilizing glucose for energy, regulating immune function, and controlling inflammation — but chronically elevated cortisol impairs muscle protein synthesis, disrupts sleep quality, increases fat storage (particularly visceral), and suppresses testosterone. For athletes, managing cortisol is as important as managing training volume and nutrition.
Cortisol follows a predictable diurnal rhythm: it peaks sharply within 30 minutes of waking (the Cortisol Awakening Response), gradually declines through the day, and reaches its lowest point during deep sleep, typically between midnight and 4 am. This morning peak is normal and essential — it mobilizes energy for the day. What disrupts recovery is cortisol failing to adequately decline by evening, which is the signature of chronic overtraining, poor sleep hygiene, high psychological stress, or excessive caffeine use.
For athletes, training itself acutely raises cortisol — this is how exercise signals adaptation. A single hard session elevates cortisol for 30–120 minutes post-workout. This acute spike is normal and necessary. Problems arise when training volume or life stress is so high that cortisol never fully returns to baseline before the next session. Signs include persistent soreness, declining performance despite consistent training, disrupted sleep, and low libido. This calculator estimates your cortisol exposure category based on training intensity, sleep quality, and lifestyle stress factors — to guide recovery optimization decisions.
Cortisol and Athletic Performance
Acutely, cortisol is essential for mobilizing energy during training. Chronically elevated cortisol (overtraining, poor sleep, high psychological stress) suppresses testosterone, impairs recovery, promotes muscle catabolism, and increases fat storage — especially visceral fat. Managing training load, sleep quality, and stress are critical for healthy T:C (testosterone-to-cortisol) ratio.