Calculate cardiac index, cardiac output, or body surface area from any two values and convert between L/min, mL/s, m², and ft² units.

Cardiac Index Calculator

Enter any 2 values to calculate the missing variable

Medical disclaimer: For informational/educational purposes only; not medical advice. Do not use this calculator to diagnose, treat, or make urgent medical decisions. Consult a licensed clinician. If you have chest pain, severe shortness of breath, fainting, or other emergency symptoms, seek emergency care.

Related Calculators

Cardiac Index Formula

CI = CO / BSA

Variables:

  • CI is the Cardiac Index (L/min/m^2)
  • CO is the cardiac output (L/min)
  • BSA is the body surface area (m^2)

To calculate Cardiac Index, divide the cardiac output by the body surface area.

References / Further Reading

For definitions, units, and clinical context, consult reputable medical references (for example, academic hospital education pages, standard cardiovascular physiology textbooks, and clinical reference resources used by clinicians). Searching for “cardiac index (CI) CO/BSA” on NIH/MedlinePlus or major cardiology organizations’ websites can also be a helpful starting point.

How to Calculate Cardiac Index?

The following steps outline how to calculate the Cardiac Index.

  1. First, determine the cardiac output (L/min). 
  2. Next, determine the body surface area (m^2). 
  3. Next, gather the formula from above = CI = CO / BSA.
  4. Finally, calculate the Cardiac Index.
  5. After inserting the variables 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.

cardiac output (L/min) = 5

body surface area (m^2) = 2.5

FAQs

What factors can affect Cardiac Output?

Several factors can affect Cardiac Output, including heart rate, blood volume, and the resistance the heart must overcome to pump blood through the body’s circulatory system.

Why is the Cardiac Index important in medical assessments?

The Cardiac Index is important because it provides a more size-adjusted measure of circulation by accounting for the patient’s body size. Clinicians may use cardiac index, along with other findings, to assess circulation in conditions such as heart failure.

Can the body surface area (BSA) vary significantly between individuals?

Yes, BSA can vary significantly between individuals based on factors like height and weight, making it crucial for personalized medical assessments such as calculating the Cardiac Index.

How can someone improve their Cardiac Output or Cardiac Index?

Improving cardiac health can involve general lifestyle habits such as appropriate physical activity, a heart-healthy diet, stress management, and avoiding smoking. If you have heart disease, concerning symptoms (for example chest pain, shortness of breath, swelling, dizziness), or take heart medications, talk with your clinician before making changes to exercise, diet, or stress routines.