Up to six percent of red dwarf stars have habitable, Earth-sized planets. Red dwarfs are the most common stars in our galaxy, so that means the closest Earth-like planet could be just 13 light-years away.
Red dwarf stars are smaller, cooler, and fainter than our Sun. An average red dwarf is only one-third as large and one-thousandth as bright as the Sun. From Earth, no red dwarf is visible to the naked eye but we are surrounded by a swarm of red dwarf stars. About 75 percent of the closest stars are red dwarfs, and so, since 6 percent of those should host habitable planets, they arrived at 13 light years as the closest Earth-like planet.