About the testosterone to estradiol (T:E2) ratio
The testosterone to estradiol ratio, usually written T:E2, is a simple way of describing the balance between total testosterone and estradiol (E2) from the same blood draw. It is not a formal diagnostic score published by a major endocrine society; it is a widely used shorthand, particularly among clinicians and patients monitoring testosterone replacement therapy (TRT), where estradiol rises alongside testosterone because some testosterone converts to estradiol through the aromatase enzyme.
How the ratio is calculated
The formula is a single division:
- T:E2 ratio = Total testosterone (ng/dL) ÷ Estradiol (pg/mL)
Labs do not always report results in those units. If your testosterone was reported in nmol/L, this calculator converts it to ng/dL by dividing by the standard conversion factor 0.0347. If your estradiol was reported in pmol/L, it converts to pg/mL by dividing by the standard conversion factor 3.671. The ratio is then calculated from the standardized ng/dL and pg/mL values so results are comparable across labs.
Putting the result in context
Some clinicians who monitor testosterone therapy informally reference a T:E2 ratio of roughly 10 to 30 as a target window: a lower ratio suggests estradiol is relatively high compared with testosterone, and a higher ratio suggests estradiol is relatively low. This window is a rule of thumb passed around in andrology and TRT practice, not a validated diagnostic cutoff, and normal testosterone and estradiol reference intervals already vary between labs and assay methods.
When to consult a professional
This calculator performs the standard division and unit conversion; it does not diagnose a hormonal imbalance and does not recommend a dose adjustment. Any change to testosterone therapy or estradiol management should be made with the clinician who ordered the labs, using the full clinical picture rather than a single ratio.