KMT-2016-BLG-1820L is a Sun-like G-type star (about 0.04 solar masses, 5,778 K), 6,260 light-years from Earth. KMT-2016-BLG-1820L b is a 4.57-Jupiter-mass companion, at 1.080 AU from its star, discovered in 2018 via microlensing. Microlensing detections occur when a foreground star's gravity briefly magnifies a background source, revealing planets that are otherwise too faint and distant to observe directly. KMT-2016-BLG-1820L b orbits at roughly the distance of Mars from the Sun. At roughly 6,260 light-years, KMT-2016-BLG-1820L lies far beyond the nearest stars yet remains reachable to large survey telescopes.