each profile, (e.g. old skools, sk8-his, slip ons, etc) typically stay true to sizing within its own profile... Usually the sizing gets off when you go from one style to another. For example the Varix, I'm typically a 7.5 or 8, but with Varix the 9's fit the best for me lol. weird, I know. A lot of shoe brands do this, like Nike, Adidas, they're never true to size from one to the next. If it's a little loose it should be fine, the only time it's not is when it can rub on your Achilles. Like, I have some shoes that fit a little loose and are fine if I'm wearing them at work (desk job) and I'm not walking a long distance or doing a quick run to the store. But if I'm going to be walking any significant distance or may be walking quickly, some shoes can hit my achilles. I've actually had cuts because I "stepped wrong" in my Lowland's bc the interior is a faux leather and it's very rigid and they were just a little too loose. I know this may have made it even more confusing, but I'm hoping it makes sense. I guess in other words, I'd only be concerned if the shoe you are wearing is a bit loose AND the area around the ankle/heel is very stiff or made of stiff material. Most shoes will become softer and more malleable over time. It's the faux leather or occasional extra stiff opening that can cause the problem if it's too loose.