A healthy result should fall into the range 2.6 - 4 pmol/L.

Triiodothyronine or T3 is the most biologically active thyroid hormone in humans. The term “free T3” means the amount of T3 that is not bound to proteins in the blood. T3 acts on almost every cell in the body by setting the metabolic rate of the cell. T3 is also critical for growth and development, especially in fetuses and children. The thyroid gland produces and releases some of the T3 in the blood, but about 80% of T3 is produced from T4 or thyroxine in the liver, kidney, and thyroid tissue. Thyroid-stimulating hormone, also known as TSH or thyrotropin is produced in the pituitary gland an stimulates the release of T3 by the thyroid gland. Most clinical laboratories do not directly measure of free T3. Instead, they measure total T3 and thyroid hormone-binding index.

Normal Ranges for Free T3:

1-23 Months 3.3-5.2 pg/mL

2-12 Years 3.3-4.8 pg/mL

13-20 Years 3.0-4.7 pg/mL

>20 Years    2.3-4.2 pg/mL














T3, Free result calculator

insert the value from you T3, Free test result.

Is your T3, Free too high or too low?
Upload your lab report and instantly interpret your result.

DIY Health One

One Lab Report Interpretation

  • One lab report interpretation
  • Use self upload form
  • 800+ biomarkers explained
  • Recommendations
  • Pay per additional interpretations
  • Report uploading support*

15 $

Analyze and Interprete Now

*Additional costs may apply

DIY Health Track

Unlimited Lab Report Interpretations

  • Unlimited lab report interpretations
  • Use self upload form
  • 800+ biomarkers explained
  • Recommendations
  • Online support
  • We do the uploading for you*

59 $/year

Analyze and Interprete Now

*4 report uploads by our team are included per year

Sign Up, Upload Tests, Get Insights and Improve with HealthMatters.io.

Sign up now

Your Privacy And Security

At HealthMatters, we're committed to maintaining the security and confidentiality of your personal information. We've put security measures in place to help protect against the loss, misuse or alteration of information under our control. We use procedural, physical and electronic security methods designed to prevent people who aren't authorized from getting access to this information. Our internal code of conduct adds additional privacy protection. See our Privacy Policy for more information.