I looked up a size 12 men’s in the conversion chart (link below) and it said 46. My DH is a size 10 US; 9.5 UK (Edward green). He did not find the Izmir comfy, but it may be bc he is a bit flat in the arch. I think the size he tried on was a 44, but I’m not sure. (I did get him H loafers in a 43 which were too small. He ended up getting an open toe sandal with a strap by Manolo Blanik in 44. Many years ago, he used to wear
Prada slides and found them comfortable too.
here is a conversion chart for men’s sizes ( US, EU)
Learn how to measure your feet and find men's shoe size in inches or centimeters and discover the perfect fit with our comprehensive men's shoe size conversion chart for US, UK, Europe, Australia, Japan, China and Mexico sizes.
www.asknumbers.com
if Possible, it might be best to measure the insole of his favorite slides and then measure the prospective insole of the Izmir?