Calculator inputs
Enter cardiac output and body size information. Large screens show three columns. Smaller screens collapse automatically for cleaner input.
Example data table
| Case | CO (L/min) | Height (cm) | Weight (kg) | BSA (m²) | HR (bpm) | CI (L/min/m²) | Status |
|---|---|---|---|---|---|---|---|
| A | 4.80 | 172 | 70 | 1.83 | 72 | 2.62 | Within range |
| B | 3.20 | 165 | 82 | 1.94 | 88 | 1.65 | Below range |
| C | 8.20 | 178 | 76 | 1.94 | 96 | 4.23 | Above range |
Formula used
Primary formula
Cardiac Index = Cardiac Output ÷ Body Surface Area
Cardiac index normalizes flow to body size. This helps compare circulation across people with different body dimensions.
Mosteller body surface area
BSA = √((Height in cm × Weight in kg) ÷ 3600)
Mosteller is simple and widely used. It balances ease, speed, and reasonable approximation for general bedside calculations.
Du Bois body surface area
BSA = 0.007184 × Height0.725 × Weight0.425
Du Bois is an older empirical equation. Some users prefer it for consistency with older references or legacy datasets.
Haycock body surface area
BSA = 0.024265 × Height0.3964 × Weight0.5378
Haycock can be useful when matching studies or workflows that rely on this specific body surface area equation.
Optional derived value
Stroke Volume = (Cardiac Output × 1000) ÷ Heart Rate
Stroke volume is shown only when heart rate is entered. It gives another view of how flow relates to each heartbeat.
How to use this calculator
- Enter cardiac output and choose the matching unit.
- Select whether body surface area should be calculated or entered directly.
- If calculating BSA, enter height, weight, and your preferred formula.
- Optionally enter heart rate to estimate stroke volume.
- Set the reference limits you want to compare against.
- Press the calculate button to view the result above the form.
- Use the chart and export buttons for reporting or review.
Frequently asked questions
1) What does cardiac index measure?
It measures cardiac output adjusted for body surface area. This makes flow comparisons more meaningful across people with different body sizes.
2) Why not use cardiac output alone?
Cardiac output alone ignores body size. A flow value that seems acceptable for one person may be inadequate or excessive for another.
3) When should I enter BSA directly?
Enter BSA directly when it is already available from a chart, monitor, or another validated calculator. This avoids recalculating it twice.
4) Which BSA formula should I choose?
Choose the formula that matches your workflow or reference source. Mosteller is common for general use because it is simple and practical.
5) What is a common reference range?
A common adult reference range is roughly 2.2 to 4.0 L/min/m². Local protocols and patient context may justify different thresholds.
6) Why is heart rate optional here?
Heart rate is not required to calculate cardiac index. It is included only to estimate stroke volume from the entered cardiac output.
7) Can this calculator replace clinical judgment?
No. It is an educational and workflow support tool. Clinical decisions should consider patient status, measurement quality, trends, and professional guidance.
8) Why do unit choices matter?
Wrong unit selection can change the result by a factor of one thousand. Always confirm whether output is entered in liters or milliliters per minute.