In the field of plasma modeling for electrical discharge machining (EDM) process, radiative losses are many times include in the energy equation using net emission coefficients (NEC). This is a sink term that accounts for the radiative emissions from the plasma to the surrounding environment. The purpose of this study is to calculate NECs for EDM arc plasmas. Two common plasma mediums, hydrocarbon oil and deionized water, are considered in this work assuming the EDM plasma is in local thermodynamic equilibrium, homogenous and isothermal. NECs are calculated for pressures of 1 and 10 bar for working temperatures commonly seen in EDM plasmas, 5,500-10,000 K. Continuum contributions such as molecular photodissociation, molecular photoionization, electron-molecule bremsstrahlung, electron-atom bremsstrahlung, ionic radiative recombination, and electron-ion bremsstrahlung are included in the calculation of NEC. In addition, the line radiations are calculated by overlapping lines considerations. Results show that radiative heat loss of EDM plasma in the deionized water dielectric medium is less than hydrocarbon oil one. Presented results for the NEC can serve as input data for various numerical models of electrical discharge machining process.