According to Bloomberg, those fleeing the Russian invasion comprise around 10 percent of Ukraine's pre-war population.
Poland has absorbed some 2.3 million of those refugees, increasing its own pre-war population by nearly seven percent in just over a month.
Other nations that have received large numbers of refugees include Romania (608,936), Moldova (387,151), Hungary (364,804), and Russia (350,172), according to the Office of the United Nations High Commissioner on Refugees. Russia's refugee count includes those who have fled from areas in eastern Ukraine controlled by Russian-backed separatists.
Russian forces have been accused of forcibly deporting thousands of Ukrainian citizens to Russia, but Russian sources claim these people are going willingly and are refugees, not hostages.
PBS NewsHour reported Monday that "fewer people have crossed the [Polish] border in recent days," suggesting that the tide of refugees is beginning to ebb.
Millions of civilians remain trapped in areas of heavy fighting. Martial law prohibits military-age males from leaving Ukraine.