Sorry didn't convert it all but 1.2= just under 4 feet. An adult corn would do well in a 20 long which is around 30 inches. While this wold work for a baby you would have to provide lots of hides. Most people start with a 10 gal 18 inches. Sorry I don't do metric but this work well:
http://www.metric-conversions.org/le...-to-inches.htm
hope this helps some