The short answer is--your true US size! We put a lot of work into getting the fit right and correcting distortions in our previous sizing, so your true size in similar styles (loafers/flats/dress shoes) should be correct. If you're still feeling uncertain, feel free to email us at hi@artemisdesignco.com. Since the intervals between EU and US sizes are different, and we've added half sizes, there aren't necessarily exact equivalents between the old and new sizing. We can help you make a choice, though! Thanks for sticking with us through this change. We know that a sizing update can be frustrating for existing customers who already loved how their Artemis shoes fit them. Our new sizing covers double the amount of sizes, so we are confident that you will find a perfect fit with our new sizing as well.