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Cardiac Index Calculator

Use our free Cardiac Index Calculator to calculate cardiac index with BSA, heart rate, and stroke volume. Get fast, accurate results with formulas.

Cardiac Index = CO ÷ BSA
L/min
Typical: 4.0 – 8.0 L/min
Typical: 1.6 – 2.2 m²

A healthy heart pumps enough blood to meet your body's needs. Still, every person has a different body size. That is why doctors often use the cardiac index instead of cardiac output alone.

Our Cardiac Index Calculator makes this job simple. It gives fast and accurate results in seconds. You can enter cardiac output and body surface area. You can also use heart rate, stroke volume, height, and weight. The calculator does the math for you.

If you have ever asked, "What is the cardiac index?" or "How do you calculate a cardiac index?", this guide will help.

What Is the Cardiac Index?

The cardiac index measures how well your heart pumps blood for your body size.

It compares cardiac output with body surface area. This gives a fair result for both small and large people.

Cardiac index is measured in L/min/m².

Doctors often use this value to check heart function. It can also help monitor people before or after heart surgery. It may also help during critical care.

A normal cardiac output does not always mean normal blood flow for every person. Body size matters. Think of it like two water pumps. One pump may work well for a small garden. A larger garden needs more water. Your body works in much the same way.

Cardiac Index Formula

The basic cardiac index formula is:

Cardiac Index = Cardiac Output ÷ Body Surface Area

Where:

  • Cardiac Output = liters of blood pumped each minute (L/min)
  • Body Surface Area = body size measured in square meters (m²)

If cardiac output is unknown, use this formula:

Cardiac Output = (Heart Rate × Stroke Volume) ÷ 1000

If body surface area is unknown, use the Mosteller formula:

Body Surface Area = Square Root of ((Height in cm × Weight in kg) ÷ 3600)

The complete formula becomes:

Cardiac Index = ((Heart Rate × Stroke Volume) ÷ 1000) ÷ Body Surface Area

How to Use the Online Cardiac Index Calculator

Our calculator offers three simple ways to calculate your cardiac index.

The first method uses cardiac output and body surface area. Enter both values. Then click the Calculate Cardiac Index button.

The second method uses heart rate, stroke volume, and body surface area. Enter all three values. The calculator first finds cardiac output. Then it calculates the cardiac index.

The third method uses height, weight, heart rate, and stroke volume. The calculator first finds your body surface area with the Mosteller formula. Next, it calculates cardiac output. Finally, it shows your cardiac index.

The result also tells you whether your cardiac index is low, normal, or high.

Example Cardiac Index Calculation

Suppose a person has these values:

Heart Rate = 72 beats per minute

Stroke Volume = 70 mL per beat

Body Surface Area = 1.85 m²

Step 1

Calculate cardiac output.

Cardiac Output = (72 × 70) ÷ 1000

Cardiac Output = 5.04 L/min

Step 2

Calculate cardiac index.

Cardiac Index = 5.04 ÷ 1.85

Cardiac Index = 2.72 L/min/m²

This value falls within the normal range.

Another example uses height and weight.

Height = 170 cm

Weight = 70 kg

Heart Rate = 72 bpm

Stroke Volume = 70 mL

First, calculate body surface area.

BSA = Square Root of ((170 × 70) ÷ 3600)

BSA = 1.82 m²

Next, calculate cardiac output.

CO = (72 × 70) ÷ 1000

CO = 5.04 L/min

Finally, calculate cardiac index.

CI = 5.04 ÷ 1.82

CI = 2.77 L/min/m²

Final Verdict

Our Cardiac Index Calculator helps you calculate cardiac index quickly and accurately. It supports several calculation methods, including a Cardiac Index Calculator with BSA. It also works with heart rate, stroke volume, height, and weight.

The calculator shows every calculation step. This makes it easy to understand the result. Whether you are a student, nurse, doctor, or simply curious, this tool saves time and reduces calculation errors.

FAQs

What is the cardiac index?

The cardiac index measures how much blood the heart pumps each minute based on body size. It is measured in liters per minute per square meter (L/min/m²).

How do you calculate a cardiac index?

Divide cardiac output by body surface area.

Cardiac Index = Cardiac Output ÷ Body Surface Area

What is a good cardiac index?

Most healthy adults have a cardiac index between 2.2 and 4.0 L/min/m². Values outside this range may need medical review.

What units does the calculator use?

Cardiac output uses liters per minute. Body surface area uses square meters. Cardiac index uses liters per minute per square meter.

Can I calculate cardiac index without knowing cardiac output?

Yes. Enter your heart rate and stroke volume. The calculator will find cardiac output first. Then it calculates your cardiac index.

Does this calculator calculate body surface area?

Yes. It can calculate body surface area automatically with the Mosteller formula when you enter your height and weight.

Is this calculator accurate?

Yes. It uses standard clinical formulas for cardiac output, body surface area, and cardiac index. The calculations match accepted medical equations.

Can I use this calculator on my phone?

Yes. The calculator works on desktops, tablets, and smartphones.