Where do your testosterone levels actually sit?
Lab reports tell you whether you're inside the "normal range." Your personal report shows something different: where your number sits against healthy young men, young men today, and young men before the decline, what controlled studies measured at your level, and whether your symptoms match it. Enter your numbers and we email it to you as a PDF.
Find these on your most recent lab report (look for Testosterone, Total, Testosterone, Free and SHBG). Labs measure free testosterone differently: Quest prints 35–155 pg/mL, while Labcorp's direct test prints about 7–25 pg/mL. Tell us which lab and we put it on one scale. With SHBG we calculate free testosterone from your total, the same way for every lab; albumin fine-tunes it (we use 4.3 g/dL if you leave it blank).
Where should we send it?
We will email your personal testosterone report as a PDF: where you rank against healthy young men, young men today and young men in 1996, what controlled studies measured at your level, and whether your symptoms match it. Over the next ten days we will send up to three short emails about what your result means; you can unsubscribe from any of them. Your information stays with Rewind.
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Without a number, the most useful thing you can do is measure. A morning fasting draw covering total testosterone, free testosterone (equilibrium dialysis preferred), and SHBG takes ten minutes and tells you exactly where you fit on the curve.
The "normal" range on a Quest or Labcorp report is calculated from the modern population — a population whose mean testosterone has fallen ~1% per year since the late 1980s. Many men in their 30s, 40s, and 50s carry numbers their lab labels "normal" that would have sat below the lower bound of healthy young men in 1990s reference data.
References. Travison TG et al., JCEM 2017;102(4):1161–1173 (modern harmonized percentiles, n=9,054, CDC LC-MS/MS) · Bhasin S et al., JCEM 2011;96(8):2430–2439 (Framingham healthy young men 19–40, n=456; total and calculated free T) · Travison TG et al., JCEM 2007;92(1):196–202 (MMAS secular decline) · Nguyen CP et al., PLOS ONE 2013 (Air Force veterans 1982–2002) · Vermeulen A, in Androgens and the Aging Male (Parthenon, 1996) · Bhasin S et al., Am J Physiol Endocrinol Metab 2001;281:E1172 / JCEM 2005;90:678 (dose-response) · Vermeulen A et al., JCEM 1999;84(10):3666–3672 (calculated free testosterone) · Morley JE et al., Metabolism 2000;49(9):1239–1242 (ADAM questionnaire).
Disclaimer. This tool and the report it sends are for educational and orientation purposes only. It does not diagnose any condition or recommend treatment. Percentiles assume LC-MS/MS testosterone measurement and a fasting morning draw. Individual decisions should be made with a qualified clinician who can integrate symptoms, comorbidities, and trends — not a single value.