Inspiratory To Expiratory Ratio Calculator

Enter the duration of inspiration and expiration into the calculator to determine the inspiratory to expiratory ratio.

Disclaimer: This calculator is for educational purposes only and is not medical advice. Do not use it to set or change ventilator settings or treatment—consult a qualified clinician for medical decisions.

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Inspiratory to Expiratory Ratio Formula

The following formula is used to calculate the inspiratory to expiratory ratio for a given duration of inspiration and expiration. In this page and calculator, IE is treated as a decimal quotient (T_i/T_e), where a colon ratio like 1:2 corresponds to 0.5.

IE = T_i / T_e

Variables:

• IE is the inspiratory to expiratory ratio (decimal form T_i/T_e)
• T_i is the duration of inspiration (any time unit; the calculator converts internally)
• T_e is the duration of expiration (any time unit; the calculator converts internally)

To calculate the inspiratory to expiratory ratio, divide the duration of inspiration by the duration of expiration.

What is an Inspiratory to Expiratory Ratio?

The inspiratory to expiratory ratio (IE ratio) is a measure used in respiratory physiology to describe the relative duration of the inspiration phase to the expiration phase during the breathing cycle. This ratio is used in clinical settings (including mechanical ventilation) as one parameter clinicians may adjust in monitored environments to support ventilation goals. A typical IE pattern for a healthy individual at rest is often described as around 1:2 (colon ratio), which corresponds to a decimal T_i/T_e of 0.5. For background reading, check standard respiratory physiology textbooks or reputable respiratory therapy/critical care education materials.

How to Calculate Inspiratory to Expiratory Ratio?

The following steps outline how to calculate the Inspiratory to Expiratory Ratio.

1. First, determine the duration of inspiration (T_i).
2. Next, determine the duration of expiration (T_e).
3. Finally, calculate the inspiratory to expiratory ratio using the formula IE = T_i / T_e.
4. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Duration of inspiration (T_i) = 2 seconds

Duration of expiration (T_e) = 4 seconds

IE (T_i/T_e) = 2 ÷ 4 = 0.5, which corresponds to a colon ratio of 1:2.