Bulgaria, with the help of the Russian Empire, achieved independence from the Ottoman Empire in 1878. In the decades before independence, Bulgaria's population had remained between 2.2 and 2.8 million people, and growth was much slower then the following century. Although most at the time assumed that it would become a Russian ally, Bulgaria defied the expectations and aligned itself with the western powers, and developed into a modern European state by the turn in the late 1800s. Bulgaria at war In the early twentieth century Bulgaria was involved in both World Wars, as well as two Balkan Wars. The Balkan states were unhappy with the borders assigned to them by the western powers, and instead wanted to re-draw them based on the dispersal of ethnic groups. This led to the first Balkan War in 1912, which saw Bulgaria fight alongside Greece and Serbia against the Ottomans. Bulgaria fought the second Balkan War on all sides, this time against Greece, Serbia, Romania and the Ottomans, as the dispute over borders continued. Bulgaria was defeated this time, and sustained heavy casualties, amassing in 58 thousand fatalities and over 100 thousand wounded in the two wars.

In the First World War, Bulgaria remained neutral at first, in order to recover from the previous wars, but then aligned itself with the Central powers in 1915, and played a vital role in maintaining their control in the Balkans. While Bulgaria was initially successful, its allies weakened as the war progressed, and then Bulgaria eventually succumbed to Allied forces and surrendered in 1918, with almost 200 thousand Bulgarians dying as a result of the war. The interwar years was a period of political and economic turmoil, and when control was re-established, Bulgaria was then able to maintain it's neutrality throughout most of the Second World War, (although there was some conflict and bombings in certain areas). Rise and fall of communism After the war, Bulgaria became a communist state, and life became harsh for the civil population there until the late 1950s when the standard of living rose again. In the late 1980s, like many Eastern European countries, Bulgaria experienced economic decline as the communist system began to collapse. Political failures also contributed to this, and approximately 300 thousand Bulgarian Turks migrated to Turkey, greatly weakening the agricultural economy. This trend of mass migration abroad continued after the fall of the iron curtain, as well as the rise of unemployment. Bulgaria reached it's peak population size in 1985 at 8.98 million inhabitants, but then the number decreases each year, and is expected to be 6.94 million in 2020. This drop in population size has been attributed to the economic collapse at the end of communism in Eastern Europe, causing many to leave the country in search of work elsewhere. Bulgaria also has one of the lowest fertility rates in the world, with 8.7 births per 1,000 people per year (in 2018).

In 2024, the total population of Bulgaria amounted to 6.44 million people. Between 1980 and 2024, the figure dropped by 2.37 million people, though the decline followed an uneven course rather than a steady trajectory. The forecast shows the total population will steadily decline by 430,000 people from 2024 to 2030.This indicator describes the total population in the country at hand. This total population of the country consists of all persons falling within the scope of the census.

Bulgaria gained its independence from the Ottoman Empire in 1878, and for the next century the population grew at a relatively constant rate, before falling into decline from the 1980s until today. The ratio of men to women in Bulgaria has remained fairly level before the 1980s, with the difference never exceeding 100,000. It was only in the 1980s when the numbers began to drift further apart, with the male population decreasing at a higher rate than females. A difference of more than 100,000 people appeared in 1988, and 200,000 at the turn of the millennium. The difference in Bulgaria's male and female populations has remained around 200,000 people for the past two decades, as the overall population has fallen from around eight million to below seven million people. This drop in population size has been attributed to the economic collapse which followed the end of communism in Eastern Europe, causing many to leave the country in search of work elsewhere. Bulgaria also has one of the lowest birth rates in the world, with just 9 births per 1,000 people in 2020.

In the Cook Islands in 2024, the population decreased by about 2.24 percent compared to the previous year, making it the country with the highest population decline rate in 2024. Of the 20 countries with the highest rate of population decline, the majority are island nations, where emigration rates are high (especially to Australia, New Zealand, and the United States), or they are located in Eastern Europe, which suffers from a combination of high emigration rates and low birth rates.

Bulgaria: Rural population, percent of total population: The latest value from 2024 is 22.96 percent, a decline from 23.3 percent in 2023. In comparison, the world average is 38.30 percent, based on data from 196 countries. Historically, the average for Bulgaria from 1960 to 2024 is 36.05 percent. The minimum value, 22.96 percent, was reached in 2024 while the maximum of 62.9 percent was recorded in 1960.

In 2023, the annual population growth in Bulgaria amounted to -3.01 percent. Between 1961 and 2023, the figure dropped by 3.97 percentage points, though the decline followed an uneven course rather than a steady trajectory.