We've all been there when we order shoes online and they don't quite fit. So here's a handy chart that has all the conversions and lengths for you.

The thing to know is, U.S. Men's sizing = U.S. Big Kids.

To be extra sure, also check any brand-specific size guides that are provided on the retailer's page.

You can also print this ruler to help check measurements as you measure heel to toe.