What is a normal cardiac output?

Normal resting cardiac output in adults is 4–8 L/min. Values below 4 L/min may indicate low-output states; values above 8 L/min at rest may reflect high-output conditions such as sepsis, hyperthyroidism, or pregnancy.

What is a normal cardiac index?

Normal cardiac index (CI) is 2.5–4.0 L/min/m². CI below 2.2 L/min/m² is often used as a threshold for cardiogenic shock. CI normalizes output for body surface area, making it more comparable across patient sizes.

What is a normal stroke volume?

Normal adult stroke volume at rest is approximately 60–100 mL per beat. It varies with preload, afterload, and contractility.

How is body surface area calculated?

This tool uses the Mosteller formula: BSA (m²) = √(height_cm × weight_kg / 3600). It is one of the most commonly used BSA formulas in clinical practice.

Can I use this tool for clinical decisions?

This tool is for education and reference only. Clinical management must be based on full patient assessment by a qualified healthcare provider.

Cardiac Output Calculator

Enter stroke volume and heart rate to calculate cardiac output and cardiac index with normal range indicators.

Hemodynamic Inputs

Stroke Volume (SV) mL/beat

Normal range: 60–100 mL/beat

Heart Rate (HR) bpm

Normal resting range: 60–100 bpm

Optional — needed for Cardiac Index

Height cm

Weight kg

Cardiac Output (CO) —

— L/min

CO = SV × HR | Normal: 4–8 L/min

Cardiac Index (CI) —

— L/min/m²

CI = CO / BSA | Normal: 2.5–4.0 L/min/m²

Body Surface Area (BSA) Mosteller formula

— m²

BSA = √(height_cm × weight_kg / 3600)

Reference Ranges

Parameter	Low	Normal	High
CO (L/min)	< 4	4–8	> 8
CI (L/min/m²)	< 2.5	2.5–4.0	> 4.0
SV (mL/beat)	< 60	60–100	> 100

Summary

This calculator computes cardiac output (CO) as the product of stroke volume and heart rate, expressed in liters per minute. When height and weight are provided, it also calculates cardiac index (CI) by dividing CO by body surface area estimated via the Mosteller formula. Both values are compared against standard normal ranges to provide quick clinical context.

How it works

Enter stroke volume (SV) in milliliters — the amount of blood ejected per heartbeat.
Enter heart rate (HR) in beats per minute.
Optionally enter height and weight to calculate body surface area (BSA) for the cardiac index.
Cardiac output is computed as CO = SV × HR, then converted from mL/min to L/min.
Cardiac index is CI = CO / BSA, normalizing output for body size.
Results are compared against accepted normal ranges with a status indicator.

Use cases

Medical students learning hemodynamic physiology and normal values.
Nurses and clinicians doing quick bedside hemodynamic estimates.
Review of cardiac physiology for board exam preparation.
ICU or critical care education on low-output states.
Comparing pre- and post-intervention cardiac output changes.
Estimating cardiac index when echocardiography data is available.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu