The potential analysis of having electric vehicles (EVs) provide regulating power has been implemented. The possible regulating power capacity from EVs and the economic return for EV users by providing regulating power are obtained. A spot price based charging schedule scenario has been used to do the day-ahead charging schedule for all EVs based on the predicted driving pattern. On top of the obtained charging schedule, the predicted EV availability and the charging schedule are used to calculate the possible regulating power capacity from EVs for both up regulating power and down regulating power. The activated regulating power and regulating power prices in the Denmark West System in 2010 have been used to calculate the economic return for EV users if all the regulating power is provided by EVs.