T3/T4 Conversion Rate

Estimate peripheral T4 to T3 conversion: approximately 80% of T3 comes from T4 deiodination. Calculate T3 equivalent: 1 mcg T4 = approximately 0.25-0.33 mcg T3. Useful for thyroid hormone replacement optimization.

Weight
Height
Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.
Advertisement

How It Works

Estimate peripheral T4 to T3 conversion: approximately 80% of T3 comes from T4 deiodination. Calculate T3 equivalent: 1 mcg T4 = approximately 0.25-0.33 mcg T3. Useful for thyroid hormone replacement optimization

Each component has a specific meaning:

  • T4 deiodination — The t4 deiodination recorded for the scenario being assessed.

Note: Interpret the t3/t4 conversion result against the thresholds and context described above.

How to Use

Enter the T4 deiodination for the scenario you are assessing. Estimate peripheral T4 to T3 conversion: approximately 80% of T3 comes from T4 deiodination. Calculate T3 equivalent: 1 mcg T4 = approximately 0.25-0.33 mcg T3. Useful for thyroid hormone replacement optimization. Use the t3/t4 conversion result to inform your calculation.

Related Calculators

TSH Zones

Medical

Levothyroxine Dose

Medical

AM Cortisol

Medical

Frequently Asked Questions