I am female and a size 10 fit perfectly. A woman's 10 is a man's 8.5. You would buy a man's 10. These are the most comfortable footwear I have ever worn; soft and lightweight. Many compliments received.
They run pretty true to size... Though if you plan wear socks with them maybe go up a size. They fit like a Croc but with a narrower footbed and toebox. If you have a wide foot this may not be the one for you