Runs fairly true to size, in both bands and cups. I think I'm a 30K at the moment and it's slightly too small, but I don't get overspill - more the cups shift down slightly throughout the day. I think a 30K would be a better fit. The wires are the narrowest I've ever seen in this size. They're about the same height as PL wires, but they hit further forwards (more on my front than under my arms), so they don't irritate my armpit. The straps are slightly more central than on the PL, so they sit flat and don't irritate. I've written an in-depth review and comparison of the S and PL bras on my blog, for anyone who wants more detail.