RF Power, EIRP and ERP Calculator
Convert dBm, milliwatts and watts. Calculate EIRP and ERP from transmitter output, antenna gain and cable loss with visible formulas.
Calculations run locally. Input values are not submitted to our server.
Result
- Transmitter power
- 30 dBm
- Milliwatts
- 1000 mW
- Watts
- 1 W
- EIRP
- 35 dBm (3.1622777 W)
- ERP
- 32.85 dBm
Worked example
30 dBm is 1 W. With 6 dBi antenna gain and 1 dB cable loss, EIRP is 35 dBm, about 3.162 W, and ERP is 32.85 dBm.
Method and assumptions
Power in dBm equals 10 × log10(power in mW). EIRP in dBm equals conducted transmitter power in dBm plus antenna gain in dBi minus cable and connector loss in dB. ERP in dBm equals EIRP minus 2.15 dB. These are engineering conversions. Permitted power depends on country, band, equipment and operating conditions; this tool does not certify compliance.
References
Calculation logic reviewed 17 October 2026. Read our methodology.