# Frequency Calculator

URL: https://speedycalculator.com/calculators/physics/frequency/
Last updated: 2026-10-30

> The frequency calculator finds the frequency and period of a wave from its speed and wavelength – with presets for light and sound in common media – or the period from a frequency.

## Inputs

- Wave velocity of
- Wave velocity v (m/s, km/h, mph, ft/s, knots, km/s)
- Wavelength λ (m, cm, mm, µm, nm, km, ft)

## Results

- Frequency f
- Period T
- Angular frequency

## Formula

```
f = v/λ,  T = 1/f
```

## Explanation

Frequency is the number of cycles per second, in hertz. Middle A on a piano is 440 Hz, Wi-Fi uses 2.4 and 5 GHz, and green light oscillates at about 560 THz. The wave speed and wavelength together fix the frequency.

### How to use the Frequency Calculator

- **Wave velocity of**
- **Wave velocity v**
- **Wavelength λ**

Results update as you type, every field has its own unit menu, and everything is calculated in your browser.

### How it works

Pick the medium to fill in the wave speed (or choose a custom speed), then enter the wavelength.

### Inputs explained

FieldWhat to enterWave velocity ofChoose one: Light in vacuum, Light in air, Light in water, Light in glass …Wave velocity vUnits: m/s, km/h, mph, ft/s, knots, km/sWavelength λUnits: m, cm, mm, µm, nm, km …

### What each result means

- **Frequency f** = [v]÷[Wavelength λ]
- **Period T** = [Wavelength λ]÷[v]
- **Angular frequency** = 2×pi×[v]÷[Wavelength λ]

### Example values

How the main result changes when **Wave velocity v** changes and everything else stays at the example values above:

Wave velocity v (m/s)Frequency f (Hz)170439.7436255439.7436340439.7436425439.7436510439.7436680439.7436

## Worked example

Inputs — Wave velocity of: Sound in air at 20 °C; Wavelength λ: 0.78 m.

Results — **Frequency f = 439.74359 Hz**; Period T = 0.002274 s; Angular frequency = 2,762.990462 rad/s.

## Key terms

- **Frequency**: Cycles per unit time.

## FAQ

**What is a hertz?**
One cycle per second.

**How are frequency and period related?**
T = 1/f.

**Does frequency change when a wave enters a new medium?**
No – the speed and wavelength change, the frequency stays the same.

**What is the audible frequency range?**
About 20 Hz to 20 kHz for young humans.


## Sources

- [OpenStax – University Physics Volume 1](https://openstax.org/details/books/university-physics-volume-1)
- [HyperPhysics (Georgia State University)](http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html)