# Aortic Valve Area Calculator (Continuity Equation)

URL: https://speedycalculator.com/calculators/health/aortic-valve-area/
Last updated: 2026-10-30

> The aortic valve area calculator estimates the opening of the aortic valve from echocardiography with the continuity equation – LVOT diameter and the velocity-time integrals in the LVOT and across the valve – and grades aortic stenosis.

## Inputs

- LVOT diameter (cm, mm)
- LVOT VTI (cm)
- Aortic valve VTI (cm)
- Height (cm, in, m, ft, mm)
- Weight (kg, lb, st, g)

## Results

- LVOT area
- Aortic valve area
- Dimensionless index
- Indexed AVA

## Formula

```
LVOT area = π × (LVOT diameter ÷ 2)²
AVA = LVOT area × VTI(LVOT) ÷ VTI(AV)
Dimensionless index = VTI(LVOT) ÷ VTI(AV)
Indexed AVA = AVA ÷ BSA
```

## Explanation

Blood flowing out of the left ventricle must all pass through the valve, so flow in the outflow tract equals flow through the valve. Aortic stenosis is severe when the valve area is below 1.0 cm² (or 0.6 cm²/m² indexed).

### How to use the Aortic Valve Area Calculator

- **LVOT diameter**
- **LVOT VTI**
- **Aortic valve VTI**
- **Height**
- **Weight**

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

### How it works

Enter the LVOT diameter measured in mid-systole and the velocity-time integrals from pulsed (LVOT) and continuous-wave (valve) Doppler. Mean velocities or peak velocities can be used instead of VTIs.

### Inputs explained

FieldWhat to enterLVOT diameterUnits: cm, mmLVOT VTIIn cmAortic valve VTIIn cmHeightUnits: cm, in, m, ft, mmWeightUnits: kg, lb, st, g

### What each result means

- **LVOT area** = pi×([LVOT diameter]÷2)^2
- **Aortic valve area** = [LVOT area]×[LVOT VTI]÷[Aortic valve VTI]
- **Dimensionless index** = [LVOT VTI]÷[Aortic valve VTI]
- **Indexed AVA** = [Aortic valve area]÷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)Aortic valve area (cm²)1.050.221.580.492.10.872.631.353.151.95
*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: 2.1 cm; LVOT VTI: 20 cm; Aortic valve VTI: 80 cm; Height: 170 cm; Weight: 75 kg.

Results — LVOT area = 3.46 cm²; **Aortic valve area = 0.87 cm²**; Dimensionless index = 0.25; Indexed AVA = 0.46 cm²/m².

## Key terms

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

## FAQ

**What is a normal aortic valve area?**
3–4 cm² in adults.

**What is severe aortic stenosis?**
Valve area below 1.0 cm², mean gradient above 40 mmHg or peak velocity above 4 m/s.

**Why is the LVOT diameter so important?**
It is squared, so a 1 mm error changes the area by about 10%.


## Sources

- [Baumgartner H et al. Recommendations on the echocardiographic assessment of aortic valve stenosis. J Am Soc Echocardiogr, 2017](https://pubmed.ncbi.nlm.nih.gov/28363204/)