T Calc

The Free Testosterone and Bioavailable Testosterone Calculator application is designed to assist clinicians in accurately determining circulating bioactive testosterone levels. Simply plug in the appropriate lab values and push a button for fast, accurate results.

How to use the Free & Bioavailable Testosterone Calculator

The Free & Bioavailable Testosterone Calculator reduces the risk of errors that can occur when performing complicated calculations by hand. To use the app, input current lab values into the specified boxes for:

• Albumin
• SHBG
• Testosterone

Once lab values are in place, press the calculate button and let the Free & Bioavailable Calculator app do the math.

Free & Bioavailable Testosterone

Testosterone and dihydrotestosterone (DHT) circulate in plasma unbound (free approximately 2-3 percent), bound to specific plasma proteins (SHBG), and weakly bound to non-specific proteins such as albumin. The SHBG-bound fraction is biologically inactive because of the high binding affinity of SHBG for testosterone.

Bioavailable testosterone measurement includes the free plus the weakly bound. Free testosterone measures the free fraction.

Certain health conditions and medications, such as corticosteroids, can affect SHBG levels, impacting total serum testosterone concentration. Combining albumin, sex hormone-binding globulin (SHBG) and testosterone levels provides a more precise measurement of total serum testosterone concentration.

Free Testosterone Reference Range Males (16 years and above): 9-30 ng/dL Females: 0.3–1.9 ng/dL

Bioavailable Testosterone Reference Range

Males: 20-29 years: 83-257 ng/dL 30-39 years: 72-235 ng/dL 40-49 years: 61-213 ng/dL 50-59 years: 50-190 ng/dL 60-69 years: 40-168 ng/dL

69 years: not established

Females (non-oophorectomized) 20-50 years (on oral estrogen): 0.8-4.0 ng/dL 20-50 years (not on oral estrogen): 0.8-10 ng/dL

50 years: not established

This website/app has been developed in part through an educational grant from Besins Healthcare (UK) Ltd. The company has no editorial control on its content.

IMPORTANT LIMITATIONS: This calculator is an educational tool and should not be solely relied upon in making any clinical decision. No responsibility whatsoever is assumed for its correctness or suitability for any given purpose. Please consult your health care provider first for any health concerns.

Additionally, the calculated free and bioavailable testosterone should not be relied upon in situations with potential massive interference by steroids binding to SHBG (e.g. in women during pregnancy, in men during treatment inducing high levels of DHT or Mesterolone.