Example data table
| Use case | Frequency | Speed | Wavelength |
|---|---|---|---|
| Ultrasonic cleaning (air) | 40 kHz | 343 m/s | 8.575 mm |
| Pipe inspection (water) | 500 kHz | 1480 m/s | 2.960 mm |
| Medical imaging (tissue) | 5 MHz | 1540 m/s | 0.308 mm |
| Aluminum flaw detection | 2.25 MHz | 6320 m/s | 2.809 mm |
| Steel thickness gauging | 10 MHz | 5960 m/s | 0.596 mm |
Formula used
- λ = v / f where λ is wavelength (m), v is sound speed (m/s), f is frequency (Hz).
- T = 1 / f (period in seconds).
- ω = 2πf (angular frequency in rad/s).
- k = 2π/λ (wavenumber in rad/m), and 1/λ (spatial frequency in 1/m).
How to use this calculator
- Select the medium, or pick custom if needed.
- Enter the frequency and choose its unit.
- Use the preset speed, or enable the override option.
- For air, enter temperature to refine the speed.
- Press Calculate to view results above the form.
- Use the download buttons to export CSV or PDF.
Ultrasonic wavelength guide
1) Why wavelength matters in ultrasound
Wavelength links frequency to what you can detect. A shorter wavelength can resolve smaller flaws and thinner layers, but it also attenuates faster in many materials. This calculator converts your selected frequency and sound speed into practical wavelength units, so you can match your setup to the target size.
2) Typical ultrasound frequency ranges
Ultrasound usually starts above 20 kHz. Cleaning and welding often run around 20–60 kHz. Industrial NDT commonly uses 0.5–10 MHz, while many medical probes operate near 1–15 MHz. As frequency rises, period drops, and the computed wavelength shrinks quickly.
3) Sound speed changes by medium
Sound speed depends on density and stiffness, so each medium yields a different wavelength at the same frequency. Air is about 343 m/s near room temperature, water about 1480 m/s, soft tissue about 1540 m/s, aluminum about 6320 m/s, and steel about 5960 m/s. Verify values for your conditions.
4) Quick wavelength examples you can compare
At 40 kHz in air, wavelength is about 8.6 mm, which suits distance sensing and cleaning. At 500 kHz in water, wavelength is about 3.0 mm, useful for inspection and ranging. At 5 MHz in tissue, wavelength is about 0.31 mm, supporting fine imaging detail.
5) Wavenumber and spatial frequency insights
Wavenumber k (rad/m) is 2π/λ. It is helpful in modeling phase, interference, and beam propagation. Spatial frequency 1/λ (1/m) grows as wavelength shrinks, which often increases sensitivity to small features but can demand better coupling and alignment.
6) Temperature effect for air measurements
Air speed increases with temperature, so wavelength increases too when frequency is fixed. Using v ≈ 331.3 + 0.606·T, air at 0°C is near 331 m/s, while at 30°C it is near 349 m/s. That change shifts wavelength by roughly 5% at the same frequency.
7) Choosing a transducer and coupling method
Pick frequency based on the smallest feature you need to resolve and the penetration you need to reach. Higher frequency improves detail but loses energy faster, especially in lossy materials. Good coupling (gel, water path, or matched wedges) reduces reflection losses and stabilizes measured results.
8) Practical checks before exporting results
Confirm that your frequency unit is correct and that the selected medium matches your test path. If you override the preset speed, ensure units are consistent. Compare wavelength in mm or µm to your target dimensions. Then export CSV for logs or PDF for reports and documentation.
FAQs
1) What is the main formula used here?
The calculator uses λ = v / f. It converts your frequency to Hz, sets sound speed in m/s, and reports wavelength in m, mm, µm, and inches with related wave quantities.
2) Is 15 kHz considered ultrasound?
No. Ultrasound typically refers to frequencies above 20 kHz. If you enter 15 kHz, the math still works, but the signal is in the upper audible range, not ultrasonic.
3) Why do my results differ from a datasheet?
Sound speed varies with temperature, alloy composition, grain direction, pressure, and salinity. Also verify frequency calibration and unit choices. For critical applications, use measured speed or the exact datasheet value and override the preset speed.
4) Which wavelength unit should I use?
Use mm for typical industrial work, µm for high-frequency probes, and inches if your documentation is imperial. The calculator reports multiple units so you can compare directly to thickness, defect size, or feature spacing.
5) What does wavenumber mean in practice?
Wavenumber relates to phase change per distance. Larger k means faster phase variation over space, which matters in interference, beam steering, and propagation models. It is derived directly from the calculated wavelength.
6) Can I use this for pulsed ultrasound?
Yes. Wavelength is defined by the center frequency of the pulse. If your pulse has a bandwidth, use the nominal center frequency to estimate wavelength, and consider the band edges for best- and worst-case resolution.
7) What should I export, CSV or PDF?
Use CSV when you want to store many runs, plot trends, or import into spreadsheets. Use PDF when you need a quick shareable report with the key computed values for a single run.