Since the start of the war on Feb. 24 until May 11, 727,205 people have registered in Germany's Central Register of Foreigners (AZR), of which 93% hold Ukrainian citizenship.
Welt am Sonntag newspaper reported on Saturday, citing Interior Ministry data.
A significant number may have travelled on to other European Union countries or returned to Ukraine, it said.
Around 40 per cent of Ukrainian refugees were minors, and women make up 81 per cent of the adult refugees registered, Welt added.
The Russian invasion has triggered a massive displacement of people, including more than eight million Ukrainians within the country, according to the latest International Organization for Migration (IOM) report.
The number of people who have fled Ukraine has passed six million, in Europe's worst refugee crisis since the end of World War Two, a UN refugee agency said on Thursday.