Radio detection of cosmic-ray induced extended air showers (EAS) has undergone an impressive
development in the last two decades. Several ultra-high energy cosmic ray experiments are
routinely detecting radio pulses in the MHz to GHz frequency range from EAS. These experimental
developments require precise knowledge of the properties of the emitted radiation in order to
interpret and analyze the collected data. We present a comparison of predicted radio pulses
emitted by EAS simulated with CoREAS and ZHAireS, the two main and most widely used
Monte Carlo simulation packages for this purpose. We have performed a set of simulations of
the radio emission in EAS induced by different primary particles, shower directions and magnetic
field configurations. We have compared the frequency spectrum of the electric field amplitude on
the ground predicted by both packages at various observer positions with respect to the shower
axis. We have used in both simulations input parameters as similar as possible, as well as a
similar realistic atmospheric refractive index as a function of altitude. In addition, we have
compared showers with very similar values of depth of shower maximum. We have found a very
good agreement, with typical relative differences of less than 10%, between the CoREAS and
ZHAireS predictions for the dominant components of the electric field in the frequency range
from a few MHz to hundreds of MHz, where most experiments exploiting the radio technique for
EAS detection operate.