A method and apparatus for selecting interleaver sizes for turbo codes is provided herein. During operation information block of size K is received. An interleaver size K′ is determined that is related to K″, where K″ from a set of sizes; wherein the set of sizes comprise K″=ap×f, pmin≦p≦pmax; fmin≦f≦fmax, wherein a is an integer and f is a continuous integer between fmin and fmax, p takes integer values between pmin and pmax, a>1, pmax>pmin, pmin>1. The information block of size K is padded into an input block of size K′ using filler bits, if needed. Encoding is performed using the original input block and the interleaved input block to obtain a codeword block using a turbo encoder. The codeword block is transmitted through the channel.