Acoustic Impedance Calculator

Find acoustic impedance from medium density and sound speed.

Density (kg/m³)

Speed of sound

Acoustic impedance (Pa·s/m) 420.18

Formula: Z = ρ·c

Step-by-step with your numbers:

1. Values used:

2. Density = 1.225 kg/m³

3. Speed of sound = 343

5. Acoustic impedance = Density x Speed of sound = 1.225 x 343 = 420.18Pa·s/m

Did we solve your problem today?

Acoustic impedance describes how much a medium resists the passage of sound.

The math behind it

Z = ρ·c, the product of density and sound speed. Mismatched impedances cause sound to reflect.

Air (ρ = 1.225, c = 343) → Z ≈ 420 Pa·s/m.

Why does it matter in ultrasound?

Impedance mismatches at tissue boundaries create the echoes that form the image.