Indo-European , Indo-Iranian , Indo-Aryan 366,000,000 [ 4 ] 366,000,000 Standard Hindi 325,000,000; A total of 650,000,000 including Urdu and secondary speakers, does not include Maithili . All Hindi dialects are mutually intelligible. 2 Spanish Indo-European , Italic , Romance 322,300,000 [ 5 ] 322,200,000 [ 6 ] Total of 417