In this article we calculate the distance covered by a popular FM Transmitter.

FM transmitters are used in many different applications like outdoor drive in movie theaters. A typical FM transmitter has a maximum output between 0.1 Watt and 25 Watt. The one below transmits at 15 Watt.

**FM Transmitter Range Calculator**

In the calculator below, enter:

- Transmitter power 15 Watt (converts to 42 dBm)
- Receiver sensitivity (consistent with Rural, Urban or Large City)
- Transmit Antenna Gain
- Receive Antenna Gain

**Example Calculation**

According to the ITU, the following table shows required sensitivity in dBuV/m for FM in various environments. We have used the dBuV/m to V/m calculator to convert the units.

Environment | Field Strength (dBuV/m) | Field Strength (V/m) |

Rural | 54 | 0.0005012 |

Urban | 66 | 0.0019953 |

Large Cities | 74 | 0.0050119 |

The field strength is used to calculate the input power at the receiver in dBm. In this case the antenna gain of 0 dBi is used. However you can substitute any value in this calculator.

The FM frequency range is 88-108 MHz.

Environment | Field Strength (V/m) | Power (dBm) |

Rural | 0.0005012 | -64 |

Urban | 0.0019953 | -52 |

Large Cities | 0.0050119 | -44 |

Note that cities are more challenging RF environments, so the required power for a certain level of performance is higher relative to a rural environment. There’s a 20 dB difference between the two. The receiver sensitivity values that can be substituted in the range calculator above.

**What is the Range of a 15 Watt FM Transmitter?**

Based on the calculation above, the range for different operating environments is:

**Rural – 44 km or 27.5 miles****Urban – 11 km or 6.9 miles****Large City – 4.4 km or 2.75 miles**

As would be expected the range is the lowest in a city where buildings and other large objects will obstruct the FM signal. This means it will not travel as far in a city as it will in a rural environment.