Abstract: The specification discloses a system for displaying a cumulative indication of the estimated cost of electrical usage in a dwelling wherein electricity is applied through an electrical supply main. A coil is inductively coupled to the supply main for generating a signal representative of the magnitude of current passing through the supply main into the dwelling. The signal is rectified and amplified and is applied to an analog-to-digital converter which periodically samples the signal to generate digital signals. Input switches are operable by the consumer in order to provide a rate indication representative of the cost of the electricity flowing through the supply main. A calculator circuit is responsive to the digital signals from the analog-to-digital converter and is responsive to the rate indication from the input switches in order to periodically calculate an estimated cost of electricity passing through the supply main at the time of sampling during a preceding period.