K2-81 is an orange K-type dwarf (about 0.75 solar masses, 4,674 K, 0.63 solar radii), 252 light-years from Earth. K2-81 b is a planet with 2.0 Earth radii, with an orbital period of 6.1 days, at 0.059 AU from its star, on an eccentric orbit (e ≈ 0.06), discovered in 2016 via transit. The planet was found when it crossed the face of its star, producing periodic dips in brightness that reveal its size and orbital period to space-based photometry. K2-81 b orbits well inside Earth's distance from the Sun.