Frequency / Wavelength Calculator
Convert between frequency and wavelength for RF design, antennas, and electromagnetic waves.
Wavelength changes with medium; frequency remains constant
Enter a value to see results
Electromagnetic Spectrum Reference
| Band | Frequency | Wavelength | Applications |
|---|---|---|---|
| ELF | 3-30 Hz | 100,000-10,000 km | Submarine comms |
| LF | 30-300 kHz | 10-1 km | AM radio, navigation |
| MF | 300 kHz-3 MHz | 1000-100 m | AM broadcast |
| HF | 3-30 MHz | 100-10 m | Shortwave, amateur |
| VHF | 30-300 MHz | 10-1 m | FM radio, TV |
| UHF | 300 MHz-3 GHz | 1 m-10 cm | WiFi, cellular, GPS |
| SHF | 3-30 GHz | 10-1 cm | Radar, satellite |
| EHF | 30-300 GHz | 10-1 mm | 5G mmWave, imaging |
| Infrared | 300 GHz-430 THz | 1 mm-700 nm | Thermal, fiber optic |
Key Formula
Where λ is wavelength, c is speed of light (299,792,458 m/s in vacuum), v is wave velocity in medium, and f is frequency. In a medium with refractive index n: v = c/n
Understanding Frequency and Wavelength
Frequency and wavelength are inversely related through the wave equation. When an electromagnetic wave travels through different media, its frequency stays constant but wavelength changes based on the medium's properties.
In Vacuum (Free Space)
The speed of light c is constant. Higher frequency = shorter wavelength.
In a Medium
Wavelength shrinks by factor n (refractive index). Frequency unchanged.
PCB and RF Design Applications
Antenna Length
Antennas are typically λ/4 (quarter wave) or λ/2 (half wave) in length. For 2.4 GHz WiFi: λ = 12.5 cm, so a quarter wave antenna is ~3.1 cm.
Transmission Lines
Trace lengths matter when approaching λ/10 of the signal frequency. At 1 GHz, λ = 30 cm, so traces >3 cm need transmission line treatment.
Via Spacing
Ground plane via stitching should be spaced <λ/20 to prevent resonance. At 5 GHz, keep via spacing under 3 mm.
Filter Design
Distributed element filters use quarter-wave stubs. Physical length depends on effective dielectric constant of PCB material.
EMC/EMI
Cables and traces can act as antennas at their resonant frequencies. Keep lengths well below λ/4 to minimize radiation.
Fiber Optics
Common wavelengths: 850 nm (multimode), 1310 nm and 1550 nm (single-mode). Frequency is in the hundreds of THz.
Common RF Frequencies
| Application | Frequency | Wavelength (air) | λ/4 Antenna |
|---|---|---|---|
| FM Radio | 88-108 MHz | ~3 m | ~75 cm |
| 433 MHz ISM | 433.92 MHz | 69 cm | 17.3 cm |
| LoRa (EU) | 868 MHz | 34.5 cm | 8.6 cm |
| LoRa (US) | 915 MHz | 32.8 cm | 8.2 cm |
| GPS L1 | 1575.42 MHz | 19 cm | 4.8 cm |
| WiFi 2.4 GHz | 2400-2483 MHz | 12.5 cm | 3.1 cm |
| WiFi 5 GHz | 5150-5850 MHz | ~5.5 cm | ~1.4 cm |
| 5G Sub-6 | 3.5 GHz | 8.6 cm | 2.1 cm |
| 5G mmWave | 28 GHz | 10.7 mm | 2.7 mm |