The relationships between total length and wet weight and between total length and standard length are presented for six flounder species from the eastern coast of Korea between 2011 and 2012: Paralichthys olivaceus (Temminck & Schlegel, 1846), Cleisthenes pinetorum (Jordan & Starks, 1904), Glyptocephalus stelleri (Schmidt, 1904), Platichthys stellatus (Pallas, 1787), Pseudopleuronectes herzensteini (Jordan & Snyder, 1901), and Pseudopleuronectes yokohamae (G€unther, 1877). The values of exponent b, estimated using nonlinear least squares of weight and length data, ranged from 3.076 to 3.469. All relationships between total length and standard length were linear (all r² > 0.948). Fisheries scientists apply these size conversions (total length calculated from standard length) to understand several aspects of the population dynamics.