There is no hard-and-fast size, but it costs publishers more to produce a larger book, and you're going to have to convince an editor that the extra text is worth it. You'll often see an authors books expand in size as they get to be more successful, and more capable of overriding their editors. Sometimes this can be good, but there are notable instances where the author clearly needs an editor riding herd on him, and doesn't get it...To the detriment of the finished product(1).
So, for a standard mass-market paperback, you're probably going to see the text fall squarely in the 400-500 page range. Exceptions happen, but they're rare. For more established authors, the sky is the limit.
1) The best example I can think of is Stephen King's The Stand. The original version was tight and punchy, but, once he got famous enough, he had it reprinted with about 300 extra pages that added nothing to the plot, which he felt had been pulled unfairly by his editor. The difference, however was between ~800 pages and ~1100 pages, so clearly even Stephen King of 1978 had enough pull to get an 800 page novel published.