Mars is considerably less than 1 light-year away from Earth. According to Cornell University, Mars orbits the Sun at an average distance of 1.5 times the Earth's mean orbital distance. At the two planets' closest approach, the distance between them shrinks to 0.5 astral units, which equals 75 million kilometers.
The maximum distance between Mars and Earth comes when the two planets are on opposite sides of the Sun. At this point, the distance between them is 2.5 astral units. Because light travels at 250,000 kilometers per second, this means that Mars ranges from 4 to as much as 20 light-minutes away.