Calculate cortisol, DHEA, or cortisol/DHEA ratio from two serum/plasma test values with unit conversion and missing-value solving.
Medical disclaimer: Educational use only; not medical advice and not for diagnosis. Do not start, stop, or change medications or supplements (including DHEA) based on this result. Discuss hormone results with a licensed clinician, especially if you are pregnant, under 18, have adrenal/pituitary disorders, or take glucocorticoids/steroid medications. Seek urgent care for severe or rapidly worsening symptoms.
About this calculator: Unit conversions used: cortisol 1 μg/dL = 27.59 nmol/L; DHEA 1 ng/dL = 0.03467 nmol/L (derived from molecular-weight conversion). To verify constants and molecular weights, check authoritative chemical references (for example, NIH PubChem entries for cortisol and DHEA) and confirm units/specimen type on your lab report. Last updated: 2026-01-01.
Cortisol/DHEA Ratio Formula
The cortisol/DHEA ratio compares cortisol and DHEA after both values are converted to the same molar unit, nmol/L. The ratio is unitless.
R = C / D
C = R * D
D = C / R
- R = cortisol/DHEA ratio, unitless
- C = cortisol concentration converted to nmol/L
- D = DHEA concentration converted to nmol/L
The calculator can solve for any one missing value when you enter the other two:
- To calculate the ratio: cortisol in nmol/L is divided by DHEA in nmol/L.
- To calculate cortisol: DHEA in nmol/L is multiplied by the ratio, then converted back to the cortisol unit you selected.
- To calculate DHEA: cortisol in nmol/L is divided by the ratio, then converted back to the DHEA unit you selected.
The unit conversions used before the ratio is calculated are:
C_{nmol/L} = C_{\mu g/dL} * 27.59D_{nmol/L} = D_{ng/dL} * 0.03467Units and Inputs Used for This Ratio
| Measurement | Accepted units | Conversion to nmol/L | Notes |
|---|---|---|---|
| Cortisol | nmol/L, μg/dL | μg/dL × 27.59 | Use serum or plasma cortisol only. |
| DHEA | nmol/L, ng/dL | ng/dL × 0.03467 | Use DHEA, not DHEA-S. |
| Ratio | Unitless | Not applicable | Both hormone values are converted to nmol/L before division. |
| Input issue | Why it matters |
|---|---|
| Cortisol and DHEA from different dates or times | The ratio is most meaningful when both values come from the same test report or the same collection time point. |
| Saliva or urine cortisol | This calculator is set up for serum or plasma cortisol concentration units, not saliva cortisol or urinary free cortisol. |
| DHEA-S entered instead of DHEA | DHEA-S is a different lab measurement and should not be substituted for DHEA in this ratio. |
Example Calculations
Example 1: Calculate the cortisol/DHEA ratio
You have a cortisol level of 400 nmol/L and a DHEA level of 8 nmol/L.
R = 400 / 8 = 50
The cortisol/DHEA ratio is 50.
Example 2: Calculate DHEA from cortisol and ratio
You have a cortisol level of 15 μg/dL and a cortisol/DHEA ratio of 40.
First convert cortisol to nmol/L:
C = 15 * 27.59 = 413.85 nmol/L
Then divide by the ratio:
D = 413.85 / 40 = 10.34625 nmol/L
The DHEA level is 10.3463 nmol/L if nmol/L is selected.
FAQ
Can I use DHEA-S instead of DHEA?
No. DHEA and DHEA-S are different lab measurements. This calculator is for DHEA only. If your report lists DHEA-S, do not enter it as DHEA.
Can I use saliva cortisol or urinary free cortisol?
No. The calculator is designed for serum or plasma cortisol values in nmol/L or μg/dL. Saliva cortisol and urinary free cortisol use different specimen types and should not be mixed into this ratio.
What does a high or low cortisol/DHEA ratio mean?
A higher ratio means cortisol is higher relative to DHEA. A lower ratio means DHEA is higher relative to cortisol. Interpretation depends on the lab method, timing of collection, reference ranges, medications, health conditions, and the reason the test was ordered. Use the result as a calculation aid, not as a diagnosis.
