Electromagnetic waves propogate through free space at the speed of light (c) which is 2.99793x108m/s - for simplicity 3x108m/s has been used to calculate the values in the table below.
The number of waves passing through a given point in one second gives the frequency of the wave (ƒ) in Hertz (Hz). The resulting wavelength is then expressed in metres (m).
| Ready-Reckoner Table | ||
| Frequency | Wavelength | Notes |
| 1 Hz | 300,000 km | |
| 50 Hz | 6,000 km | European Mains Frequency |
| 60 Hz | 5,000 km | USA Mains Frequency |
| 100 Hz | 3,000 km | |
| 1 kHz | 300 km | |
| 10 kHz | 30 km | |
| 100 kHz | 3 km | |
| 1 MHz | 300 m | |
| 10 MHz | 30 m | |
| 100 MHz | 3 m | FM Radio |
| 900 MHz | 330 mm | GSM Cellular communications (Vodafone and Cellnet in the UK) |
| 1 GHz | 300 mm | |
| 1.8 GHz | 170 mm | GSM Cellular communications (DCS 1800/PCN, Orange and One 2 One in the UK) |
| 1.9 GHz | 157 mm | GSM Cellular communications (PCS) |
| 2.2 GHz | 140 mm | Third generation mobile communications (UMTS) |
| 2.4 GHz | 125 mm | Microwave ovens, approximate resonant frequency of water |
| 10 GHz | 30 mm | |
| 18 GHz | 17 mm | |
| 40 GHz | 7.5 mm | |