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Testosterone unit converter

Convert one existing laboratory blood testosterone result between the matching units for the same reported measurement: total testosterone between ng/dL and nmol/L, or free testosterone from pg/mL or ng/dL to pmol/L and back.

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Calculate your result

Enter one number exactly as printed on the laboratory report, then choose the matching total or free conversion mode.

Accepted range: 0 to 10000 ng/dL (total)

Your result will appear here

Nothing is saved or added to the URL.

What this result means

First choose the mode that matches both the laboratory label and unit. Convert total testosterone only between ng/dL and nmol/L. For free testosterone, use the explicitly labelled Free mode for pg/mL, ng/dL or pmol/L. A unit conversion cannot turn a total result into a free result. [1][2][3][4]

Total and free testosterone are different measurements

A total testosterone test includes testosterone that is bound to proteins plus the unbound fraction. A free testosterone test measures only the unattached form. Their numbers must not be converted into each other as though they were two units for the same reported quantity. [4]

Choose the mode from the report label and unit

Use a Total mode only when the report says total testosterone and shows ng/dL or nmol/L. Use a Free mode only when the report says free testosterone and shows pg/mL, ng/dL or pmol/L. The explicit Free ng/dL mode prevents that unit from being mistaken for Total ng/dL. Bioavailable testosterone, calculated free testosterone and other unit pairs are outside this calculator. [1][2][4]

Why official factors differ in the last digit

Labcorp lists 0.03467 nmol/L for each ng/dL of total testosterone and 3.4674 pmol/L for each pg/mL of free testosterone, equivalent to 34.674 pmol/L per ng/dL. Mayo publishes slightly different displayed factors: 0.0347 for total and 34.672 for free, while the Siemens total-testosterone assay uses 0.0347. This calculator deliberately pins the Labcorp factors for internally consistent forward and reverse conversions. [1][2][3]

This calculator pins the more detailed Labcorp forward factors and derives each reverse factor as its exact reciprocal. It does not combine a separately rounded forward factor with a separately rounded reverse factor, which would make a round trip drift unnecessarily. [1]

How the result is rounded

The engine stores each factor as bounded integers over integers and rounds once to two decimals for display. A displayed decimal explains the conversion but cannot add analytical precision to the source laboratory result. [1][2][3]

What the conversion cannot tell you

A converted value is not a reference-range result, diagnosis or treatment recommendation. The same number can need different context depending on whether the test is total, free or bioavailable, how it was measured, the laboratory interval, timing, symptoms and other results. [4]

The calculator never estimates free testosterone from total testosterone, SHBG and albumin. That is a different clinical model with additional assumptions and is not unit conversion. [4]

Safe next steps

Keep the original test name, value, unit, collection time, laboratory method and reference interval beside the converted number. Use the result only to compare the same reported measurement in equivalent units. For interpretation or treatment decisions, use the complete original report and qualified professional advice. [4]

Formula and assumptions

Formula
Total: nmol/L = ng/dL × 0.03467; ng/dL = nmol/L ÷ 0.03467. Free: pmol/L = pg/mL × 3.4674 or ng/dL × 34.674; reverse each conversion with the exact reciprocal. [1][2][3]
Version
Total and free testosterone mass-to-amount unit conversion, labcorp-mayo-siemens-testosterone-unit-conversion-v1
Rounding
Represent each published forward factor as an exact integer ratio, use the exact reciprocal for the reverse mode, and round once to two decimals. Exact halfway ties round upward in magnitude; a positive value below display resolution uses a less-than result.
Worked example
For a total testosterone result of 500 ng/dL: 500 × 0.03467 = 17.335 nmol/L, displayed as 17.34 nmol/L. Separately, a free testosterone result of 100 pg/mL—or the equivalent source value 10 ng/dL—converts to 346.74 pmol/L. The total and free examples are different reported measurements and are not interchangeable. [1][2][3]

Who this is for — and when not to use it

Intended use

Neutral, reversible unit conversion for a person who already has one laboratory blood testosterone result explicitly labelled total or free and needs that same measurement expressed in its matching alternative reporting unit.

Not intended for

This tool does not convert total testosterone into free or bioavailable testosterone, estimate free testosterone from total testosterone, SHBG or albumin, interpret a result, apply a reference interval, diagnose a condition, recommend hormone treatment or guide a dose.

Exclusions

  • Conversion between total, free and bioavailable testosterone measurements
  • Calculated free or bioavailable testosterone equations using total testosterone, SHBG or albumin
  • Reference ranges, health bands, diagnosis, symptom assessment and treatment thresholds
  • Medication, hormone therapy, supplement or dose decisions
  • Saliva, urine, dried blood spot or any measurement not reported as a laboratory blood result
  • Any hormone or analyte other than testosterone
  • Changing, correcting or reconstructing precision absent from the source laboratory result

Evidence sources

  1. 1. Endocrinology conversion tables: mass concentration and SI units — Labcorp Endocrinology Center of Excellence. Accessed Aug 12, 2026.
  2. 2. International System of Units conversion table — Mayo Clinic Laboratories. Accessed Aug 12, 2026.
  3. 3. Testosterone II assay instructions for use — Siemens Healthineers. Accessed Aug 12, 2026.
  4. 4. Testosterone levels test — MedlinePlus, U.S. National Library of Medicine. Accessed Aug 12, 2026.