Reverse T3 Ratio Calculator



The thyroid gland plays a crucial role in regulating metabolism and maintaining hormonal balance in the body. An imbalance in thyroid hormones, particularly Reverse T3 (rT3), can have significant health implications. The rT3 ratio is calculated by comparing the levels of rT3 to other thyroid hormones like Free T3 (fT3) or Total T3 (T3). This ratio can provide insights into whether the thyroid is functioning optimally or if there are underlying issues that need attention.


The Reverse T3 Ratio Calculator uses a simple formula to determine the rT3 ratio:

Reverse T3 (rT3) Ratio = (rT3 Level / fT3 or T3 Level) x 100


  • rT3 Level is the concentration of Reverse T3 in the blood.
  • fT3 or T3 Level is the concentration of Free T3 or Total T3 in the blood.

How to Use?

Utilizing the Reverse T3 Ratio Calculator is a straightforward process:

  1. Collect Blood Test Results: Obtain the results of your recent thyroid panel blood test, including the levels of rT3 and either fT3 or T3.
  2. Input Values: Enter the values into the calculator, specifying the rT3 level and the corresponding fT3 or T3 level.
  3. Calculate Ratio: Use the calculator to compute the rT3 ratio by applying the formula: (rT3 Level / fT3 or T3 Level) x 100.
  4. Interpret Results: Review the calculated ratio to gain insights into your thyroid health. A balanced ratio is generally indicative of healthy thyroid function, while imbalances may suggest the need for further evaluation or treatment.


To illustrate how to use the Reverse T3 Ratio Calculator, let’s consider an example:

Suppose your recent blood test results indicate an rT3 level of 20 ng/dL and a Total T3 level of 100 ng/dL. To calculate the rT3 ratio:

Reverse T3 (rT3) Ratio = (20 ng/dL / 100 ng/dL) x 100 = 20%

In this case, your rT3 ratio is 20%, which can provide insights into your thyroid health status.


Q1: What does a high rT3 ratio indicate? A1: An elevated rT3 ratio may suggest a condition known as thyroid hormone resistance or indicate that the body is converting too much T4 hormone into rT3, potentially impairing thyroid function.

Q2: Can I use this calculator for self-assessment? A2: While the calculator can provide insights, it’s important to consult a healthcare professional for a comprehensive evaluation and interpretation of thyroid health.

Q3: Is a high rT3 ratio always a cause for concern? A3: Not necessarily. A high ratio should prompt further evaluation by a healthcare provider to determine the underlying cause and appropriate management.


The Reverse T3 Ratio Calculator is a valuable tool for individuals and healthcare professionals alike to assess thyroid health quickly and conveniently. By calculating the rT3 ratio, individuals can gain insights into the functioning of their thyroid gland and potentially identify issues that may require further attention. While the calculator is a useful resource, it should be used in conjunction with professional medical guidance to ensure comprehensive thyroid health management. Maintaining thyroid health is crucial for overall well-being, and this calculator can play a pivotal role in achieving that goal.

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