A display device includes an emission level calculator and a display. On the basis of a first route for a vehicle from an origin to a destination and electricity information of electricity stored in an in-vehicle battery in which electricity to be used for travel of the vehicle is stored, the emission level calculator calculates a first emission level of carbon dioxide to be caused by travel of the vehicle on the first route. Furthermore, on the basis of a second route for public transportation from the origin to the destination, the emission level calculator calculates a second emission level of carbon dioxide to be caused by travel of the public transportation on the second route. The display displays information based on the first emission level and the second emission level.