Afternoon or evening cortisol optimal range and reference range

Compiled by Alina Radu, founder of Sera, from the published sources below · Last reviewed November 9, 2026

Sera's bands for Afternoon or evening cortisol:

  • Optimal 2 – 8 μg/dL (55 – 221 nmol/L); sufficient 2 – 11 μg/dL (55 – 303 nmol/L); out of range below 2 or above 11 μg/dL.

Evidence grade: Published reference interval. A band that primarily reflects a published adult laboratory or population reference interval. It is not necessarily applicable to every assay or laboratory.

At Sera's last range review a change to this band was proposed and held, because the evidence for it was thin, so the band is unchanged. The note below says where it matches published intervals and where it does not.

All units

UnitOptimalSufficientOut of range
μg/dL2 – 82 – 11below 2 or above 11
nmol/L55 – 22155 – 303below 55 or above 303
ng/mL20 – 8020 – 110below 20 or above 110

What the evidence says

For an afternoon or evening sample. The lower edge of 2 μg/dL matches Mayo Clinic Laboratories' p.m. interval of 2 to 14; the acceptable upper edge of 11 is close to Labcorp's 11.9 and matches neither exactly. No guideline sets a threshold for an afternoon serum cortisol, and the optimal ceiling of 8 is a functional target with no published source.

Sources

  • CORT - Overview: Cortisol, Serum — Mayo Clinic Laboratories, 2026 · Laboratory / reference-interval sourceAdults, p.m. sample: 2 to 14 mcg/dL. Matches Sera's lower edge of 2 and supports a sufficient upper edge of 14.
  • Cortisol — Labcorp, 2026 · Laboratory / reference-interval sourcePM reference interval 2.3 to 11.9 μg/dL, a lower ceiling than Mayo's on a different assay.

What Cortisol (Afternoon/Evening) measures

Your cortisol level in the afternoon or evening, which shows your daily cortisol rhythm.

This should be lower than your morning level. A flat curve through the day can be a sign of long-term stress.

Related hormone health markers

See Afternoon or evening cortisol in the full list of biomarker ranges

About the author

Alina Radu is the founder of Sera and a software engineer. The idea started with her own Hashimoto's tests, scattered across years without the big picture. She is not a clinician: these ranges are compiled from the published sources linked on each page, with every source named. Alina Radu on LinkedIn

This page is a reference for practitioners, not medical advice. Sera's bands are practitioner targets for structured review, not diagnostic thresholds, and Sera does not diagnose or recommend treatment. Read a result alongside the interval printed by the issuing laboratory and the client's history and symptoms. Range set: Sera Production, version 1.0, last reviewed November 9, 2026.