Trianon Hungary emerged from World War I with reduced borders roughly coterminous with Hungary's present-day borders. In 1920 Hungary had about 8 million inhabitants, and by 1941 the population had grown to around 9.3 million. But the nation lost about 5 % of its population in World War II, so as of 1949 the population was only about 8.8 million. Thereafter, the growth rate of the population fluctuated substantially. Until the mid-1950s, high fertility and declining mortality caused rapid population growth. In 1954 the highest postwar live-birth rate was reached, at 23 births per 1,000 population. consequently, until the mid-1960s the birth rate declined, but the mortality rate was also low. In the late 1960s and early 1970s, the birth rate again rose, partly because of demographic measures introduced by the government in 1967 and 1973. Because the overall population had begun to age, the mortality rate also increased during this time, but it was counterbalanced by the higher rate of live births.

The population of Hungary (2001 estimate) is 10,106,017. The overall population density is 109 persons per sq km (281 per sq mi). Urban areas are home to 66 % of the population. From its inception in the 11th century, the Kingdom of Hungary was a multi-ethnic nation. Major territorial changes made Hungary ethnically homogenous after World War I, and more than nine-tenths of the population is now ethnically Hungarian and speaks Hungarian as its mother tongue. The Hungarian language is classified as a member of the Ugric branch of the Uralic languages; as such it is most closely related to the Ob-Ugric languages, Khanty and Mansi, which are spoken east of the Ural Mountains. It is also related, though more distantly, to Finnish and Estonian, each of which is a national language; to the Sami languages of far northern Scandinavia; and, more distantly still, to the Samoyedic languages of Siberia. Ethnic Hungarians are a mix of the Finno-Ugric Magyars and various assimilated Slavic, Turkish, and Germanic peoples. About 3 % of the population is Gypsy (Rom), and nearly another 5 % is made up of Slovaks, Romanians, Croats, Germans, and others.