Thyroid

Free T4 unit converter

Active thyroid hormone (thyroxine)

Also known as: Free thyroxine, T4L, Freies Thyroxin, Thyroxine libre, T4 libre, Tiroxina libre

Converter

Enter a value in any unit and all other units fill in.

ng/dL pmol/L ng/L

Worked example

17.4 pmol/L (middle of the reference range) = 1.35 ng/dL

Conversion formulas

ng/dL	ng/dL = pmol/L × 0.0777	pmol/L = ng/dL × 12.87
ng/L	ng/L = pmol/L × 0.7769	pmol/L = ng/L × 1.287

Reference range

Unit	Adults
ng/dL	0.8003 – 1.904
pmol/L	10.3 – 24.5
ng/L	8.002 – 19.03

Source: MedlinePlus (NLM): Free T4 test · Last reviewed: 2026-10-14

Note from the source: 0.8-1.9 ng/dL (10.3-24.5 pmol/L); based on a large population and not necessarily normal for an individual (MedlinePlus)

Frequently asked questions

How do I convert Free T4 from pmol/L to ng/dL?

ng/dL = pmol/L × 0.0777. In the other direction: pmol/L = ng/dL × 12.87.

What is the reference range of Free T4?

For adults the range is 10.3 – 24.5 pmol/L (MedlinePlus (NLM): Free T4 test). Reference ranges differ between laboratories and partly by sex and age; use the range printed on your lab report.

Which units are used for Free T4?

Common units are ng/dL, pmol/L, ng/L.