Optical fiber communication networks play an important role in the global telecommunication network. However, nonlinear effects in the optical fiber and transceiver noise greatly limit the performance of fiber communication systems. In this paper, the product of mutual information (MI) and communication bandwidth is used as the metric of the achievable information rate (AIR). The MI loss caused by the transceiver is also considered in this work, and the bit-wise MI, generalized mutual information (GMI), is used to calculate the AIR. This loss is more significant in the use of higher-order modulation formats. The AIR analysis is carried out in the QPSK, 16QAM, 64QAM and 256QAM modulation formats for the communication systems with different communication bandwidths and transmission distances based on the enhanced Gaussian noise (EGN) model. The paper provides suggestions for the selection of the optimal modulation format in different transmission scenarios.Graphical Abstract