Embodiments of a broadcast receiver and method for optimizing a scale factor in a log-likelihood ratio (LLR) mapper are generally described herein. In some embodiments, the broadcast receiver includes an LLR mapper to generate LLRs from demodulated data samples, a low-density parity-check (LDPC) decoder to generate decoded data from the LLRs, and an LLR optimizer to dynamically select a scale factor for the LLR mapper based on a number of iterations for convergence of the LDPC decoder. In some embodiments, the LLR optimizer iteratively revises the scale factor during receipt of broadcast signals until the number of iterations of the iterative decoder is either minimized for convergence or minimized for convergence failures.