The electrical energy losses for the entire Colombian network comprising distribution voltage levels up to the high voltage transmission levels are calculated. The energy losses are classified as ``physical'' losses corresponding to Joule effect (I2R), Corona and core transformer losses and ``black'' losses which are defined as the difference between the energy available at the consumer level and the energy effectively billed by the different electric utilities in Colombia. A new methodology for calculating the ``physical'' losses is presented which is extensively based in the use of computerized methods including state estimation for the high voltage network and radial load flow for the distribution levels. The ``black'' losses including metering errors, theft and billing errors are calculated with statistical methods also using computerized tools. The results obtained highlight the importance of the losses in terms of loss of revenue for the electrical energy utilities.