Shoe size for toddler?

Bethany

So my son is needing new shoes. He’s my first and as his feet are getting bigger I’m getting confused with the size. His feet are very wide so he’s picky about brands. I’ve tried off brand shoes and they just don’t work for him, so I’ve only ever bought him nike. His feet measure 7 inches and it says 13.5 c but I’m not finding that size anywhere.