An improved method and apparatus for measuring the total energy delivered to a patient during an electrosurgical procedure. An electrosurgical target (the patient) is positioned atop a dispersive plate constituting a first electrode. The patient is included in the circuit comprising an electrosurgical generator, the plate electrode and a surgical instrument constituting a second electrode. A mathematical relationship between the current in the circuit and the load impedance is established for selected power settings of said generator. Current in the circuit is measured during electrosurgery by suitable means such as a current transformer. A computing device such as a microprocessor determines the impedence according to the relationship between current and impedence for the particular generator power setting being used. The microprocessor then computes the power delivered to the patient from the current and impedance values. The delivered power is integrated over time to determine the total energy delivered to the patient. The microprocessor may be further programmed to shut off the generator when a selected maximum total energy is delivered.