I have gone to the manufacturer's sites (I tend to avoid Amazon for purchases over about $50, because fraud). They usually have something like "If you are a 10

I have gone to the manufacturer's sites (I tend to avoid Amazon for purchases over about $50, because fraud). They usually have something like "If you are a 10.5 for Adiddas, then you are a 10 for us" kind of thing. Those have worked for me.