What is EIRP?
Effective Isotropic Radiated Power (EIRP) is the amount of power a theoretical isotropic antenna would need to emit to produce the same signal strength as your actual transmitter and antenna combination in its strongest direction.
The formula
In logarithmic (dB) form the calculation is simple addition and subtraction: EIRP (dBm) = Transmitter Power (dBm) + Antenna Gain (dBi) − Cable and Connector Losses (dB). The result is then converted to watts using EIRP(W) = 10(EIRPdBm/10) ÷ 1000.
EIRP is widely used in wireless system design and regulatory compliance (many jurisdictions cap EIRP for unlicensed bands), so double-check your region’s limits before deploying a real system. This tool is for general planning and educational purposes.
Last reviewed August 2026