According to some embodiments, a method for use in a wireless receiver comprises determining a transport block size, TBS, for a transport block to be communicated between the wireless transmitter and a wireless receiver via a physical channel transmission. The TBS determination uses a formula accounting for cyclic redundancy check, CRC, bits. The method further comprises transmitting the transport block according to the determined TBS. In particular embodiments the formula is based on an approximate transport block size, a number of code blocks, at least one of a number of CRC bits attached to the transport block, and a number of CRC bits added to each of the C code blocks.