# Doppler Echo Cardiac Output Calculator

URL: https://speedycalculator.com/calculators/health/doppler-echo-cardiac-output/
Last updated: 2026-10-30

> The Doppler echo cardiac output calculator estimates stroke volume, cardiac output and cardiac index from the LVOT diameter and the LVOT velocity-time integral measured on echocardiography.

## Inputs

- LVOT diameter (cm, mm)
- LVOT VTI (cm)
- Heart rate (bpm)
- Height (cm, in, m, ft, mm)
- Weight (kg, lb, st, g)

## Results

- Stroke volume
- Cardiac output
- Cardiac index
- LVOT VTI

## Formula

```
LVOT area = π × (diameter ÷ 2)²
SV = LVOT area × LVOT VTI
CO = SV × HR ÷ 1000
CI = CO ÷ BSA
```

## Explanation

Echo-Doppler measures how far a column of blood travels with each beat (the VTI); multiplying by the cross-sectional area of the outflow tract gives stroke volume without any invasive monitoring. An LVOT VTI below about 18 cm suggests low stroke volume.

### How to use the Doppler Echo Cardiac Output Calculator

- **LVOT diameter**
- **LVOT VTI**
- **Heart rate**
- **Height**
- **Weight**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Measure the LVOT diameter in the parasternal long-axis view and the LVOT VTI with pulsed-wave Doppler in the apical five-chamber view.

### Inputs explained

FieldWhat to enterLVOT diameterUnits: cm, mmLVOT VTIIn cmHeart rateIn bpmHeightUnits: cm, in, m, ft, mmWeightUnits: kg, lb, st, g

### What each result means

- **Stroke volume** = pi×([LVOT diameter]÷2)^2×[LVOT VTI]
- **Cardiac output** = [Stroke volume]×[Heart rate]÷1000
- **Cardiac index** = [Cardiac output]÷sqrt([Height]×[Weight]÷3600)

### Example values

How the main result changes when **LVOT diameter** changes and everything else stays at the example values above:

LVOT diameter (cm)Cardiac output (L/min)11.11.52.4724.42.56.8739.9417.59
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — LVOT diameter: 2 cm; LVOT VTI: 20 cm; Heart rate: 70 bpm; Height: 175 cm; Weight: 75 kg.

Results — Stroke volume = 63 mL; **Cardiac output = 4.4 L/min**; Cardiac index = 2.3 L/min/m²; LVOT VTI = Normal (18–22 cm).

## Key terms

- **LVOT**: Left ventricular outflow tract.
- **VTI**: Velocity-time integral.

## FAQ

**What is a normal LVOT VTI?**
About 18–22 cm.

**Why use echo to measure cardiac output?**
It is non-invasive and can be repeated to see the effect of fluids or medicines.

**What limits accuracy?**
Measuring the LVOT diameter precisely and aligning the Doppler beam with flow.


## Sources

- [Lang RM et al. Recommendations for cardiac chamber quantification by echocardiography. J Am Soc Echocardiogr, 2015](https://pubmed.ncbi.nlm.nih.gov/25559473/)