The accuracy of the procedure that converts the experimentally determined electron spectrum associated with fission of the nuclear fuels ^{235}U, ^{239}Pu, ^{241}Pu, and ^{238}U into the $\barν_e$ spectrum is examined. By using calculated sets of mutually consistent spectra it is shown that the conversion procedure can result in a small $\sim$1% error provided several conditions are met. Chief among them are the requirements that the average nuclear charge as a function of the $β$ decay endpoint energy is independently known and that the $\barν_e$ spectrum is binned into bins that are several times larger than the width of the slices used to fit the electron spectrum.

Accepted for publication in Phys. Rev. C