The calculator estimates your current energy usage based on your annual kilowatt hour (kWh) usage, your bill amount or the answers to the estimator questions provided.
It takes (or calculates) your current kWh usage by comparing the data you supply with the unit costs of your current tariff. Next, this is multiplied against the kWh unit costs of other tariffs provided by other suppliers in your area.
Any additional savings offered by the supplier based on payment or billing types are also taken into account. The estimated annual savings figure is calculated by subtracting the costs of other tariffs from your current costs.