Canonical: https://echosuite.app/guides/acoustic/

# Acoustic impedance and intensity calculator

Explore acoustic impedance and intensity with the method’s inputs, acquisition guidance and source references. Open the calculator to enter measurements or try an illustrative worked example.

Created by [Mohammed Kamareddine, MD](https://echosuite.app/about/) · [Sources & educational scope](https://echosuite.app/about/)

[Open interactive calculator →](https://echosuite.app/calculators/#acoustic)

## Method

Z = ρc; R = ((Z₂ − Z₁) ÷ (Z₂ + Z₁))²; I = P ÷ A

Use the measurement units shown below. Some fields apply only to a selected method or condition; follow the interactive tool’s method choices. The interactive tool keeps missing measurements incomplete and provides its method-specific results and reference context.

## Measurements and acquisition

### Calculate

Enter the measured value in the displayed unit

- Impedance
- Reflection
- Intensity
- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Density · ρ  kg/m³

Enter the measured value in the displayed unit

- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Sound speed · c  m/s

Enter the measured value in the displayed unit

- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Medium 1 · Z₁  MRayl

Enter the measured value in the displayed unit

- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Medium 2 · Z₂  MRayl

Enter the measured value in the displayed unit

- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Acoustic power · P  W

Enter the measured value in the displayed unit

- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

### Beam area · A  cm²

Enter the measured value in the displayed unit

- Confirm the variable matches the selected formula.
- Use the unit displayed beside the field.
- Keep measurements from the same representative hemodynamic state.

## Sources and method context

OpenStax · Rice University · 2022 · College Physics 2e · Ultrasound · §17.7 · equations 17.38–17.39; §17.3 · intensity

[Primary reference](https://openstax.org/books/college-physics-2e/pages/17-7-ultrasound)

- Acoustic relationships · §17.7 · impedance and intensity reflection; §17.3 · power per area

Z = density × sound speed. Normal-incidence intensity reflection follows the squared impedance ratio; transmission is the remaining fraction in the lossless model. I = P/A is mean power per beam area, not a clinical output index.

Catalogue review status: Source mapped · clinical sign-off pending

These pages describe the educational tool. Interpret measurements with the complete clinical context and the method’s acquisition limitations.

## Keep exploring

- [Wave relationships calculator](https://echosuite.app/guides/wave-relations/)
- [Pulse repetition and Nyquist calculator](https://echosuite.app/guides/pulse-repetition/)
- [Pulse length and near field calculator](https://echosuite.app/guides/pulse-geometry/)
- [Doppler equation calculator](https://echosuite.app/guides/doppler-equation/)

[All echo guides](https://echosuite.app/guides/) · [Learning paths](https://echosuite.app/learn/)