Effective Isotropic Radiated Power (EIRP) is the total power that would have to be radiated by a hypothetical isotropic antenna (radiating equally in all directions) to give the same signal intensity as the actual antenna in the direction of its maximum gain.

It accounts for the transmitter power, losses in the transmission line, and the gain of the antenna. EIRP is a standard measure used for regulatory compliance in wireless communications. Note: Do not confuse with ERP (Effective Radiated Power), which references a dipole antenna instead.